diff --git a/src/components/App.jsx b/src/components/App.jsx
index 839129d..d1e3902 100644
--- a/src/components/App.jsx
+++ b/src/components/App.jsx
@@ -36,6 +36,7 @@ import tokens from '../config/tokens.json'
 import isEqual from 'lodash.isequal'
 import Debug from '../libs/debug'
 import queryUtil from '../libs/query-util'
+import {formatLayerId} from './util/format';
 
 import MapboxGl from 'mapbox-gl'
 
@@ -325,6 +326,30 @@ export default class App extends React.Component {
     };
 
     const errors = validate(newStyle, latest) || [];
+
+    // The validate function doesn't give us errors for duplicate error with
+    // empty string for layer.id, manually deal with that here.
+    const layerErrors = [];
+    if (newStyle && newStyle.layers) {
+      const foundLayers = new Map();
+      newStyle.layers.forEach((layer, index) => {
+        if (layer.id === "" && foundLayers.has(layer.id)) {
+          const message = `Duplicate layer: ${formatLayerId(layer.id)}`;
+          layerErrors.push({
+            message,
+            parsed: {
+              type: "layer",
+              data: {
+                index,
+                message,
+              }
+            }
+          });
+        }
+        foundLayers.set(layer.id, true);
+      });
+    }
+
     const mappedErrors = errors.map(error => {
       const layerMatch = error.message.match(/layers\[(\d+)\]\.(?:(\S+)\.)?(\S+): (.*)/);
       if (layerMatch) {
@@ -347,7 +372,7 @@ export default class App extends React.Component {
           message: error.message,
         };
       }
-    })
+    }).concat(layerErrors);
 
     let dirtyMapStyle = undefined;
     if (errors.length > 0) {
@@ -437,56 +462,50 @@ export default class App extends React.Component {
     this.onStyleChanged(changedStyle)
   }
 
-  onLayerDestroy = (layerId) => {
+  onLayerDestroy = (index) => {
     let layers = this.state.mapStyle.layers;
     const remainingLayers = layers.slice(0);
-    const idx = style.indexOfLayer(remainingLayers, layerId)
-    remainingLayers.splice(idx, 1);
+    remainingLayers.splice(index, 1);
     this.onLayersChange(remainingLayers);
   }
 
-  onLayerCopy = (layerId) => {
+  onLayerCopy = (index) => {
     let layers = this.state.mapStyle.layers;
     const changedLayers = layers.slice(0)
-    const idx = style.indexOfLayer(changedLayers, layerId)
 
-    const clonedLayer = cloneDeep(changedLayers[idx])
+    const clonedLayer = cloneDeep(changedLayers[index])
     clonedLayer.id = clonedLayer.id + "-copy"
-    changedLayers.splice(idx, 0, clonedLayer)
+    changedLayers.splice(index, 0, clonedLayer)
     this.onLayersChange(changedLayers)
   }
 
-  onLayerVisibilityToggle = (layerId) => {
+  onLayerVisibilityToggle = (index) => {
     let layers = this.state.mapStyle.layers;
     const changedLayers = layers.slice(0)
-    const idx = style.indexOfLayer(changedLayers, layerId)
 
-    const layer = { ...changedLayers[idx] }
+    const layer = { ...changedLayers[index] }
     const changedLayout = 'layout' in layer ? {...layer.layout} : {}
     changedLayout.visibility = changedLayout.visibility === 'none' ? 'visible' : 'none'
 
     layer.layout = changedLayout
-    changedLayers[idx] = layer
+    changedLayers[index] = layer
     this.onLayersChange(changedLayers)
   }
 
 
-  onLayerIdChange = (oldId, newId) => {
+  onLayerIdChange = (index, oldId, newId) => {
     const changedLayers = this.state.mapStyle.layers.slice(0)
-    const idx = style.indexOfLayer(changedLayers, oldId)
-
-    changedLayers[idx] = {
-      ...changedLayers[idx],
+    changedLayers[index] = {
+      ...changedLayers[index],
       id: newId
     }
 
     this.onLayersChange(changedLayers)
   }
 
-  onLayerChanged = (layer) => {
+  onLayerChanged = (index, layer) => {
     const changedLayers = this.state.mapStyle.layers.slice(0)
-    const idx = style.indexOfLayer(changedLayers, layer.id)
-    changedLayers[idx] = layer
+    changedLayers[index] = layer
 
     this.onLayersChange(changedLayers)
   }
@@ -645,9 +664,8 @@ export default class App extends React.Component {
     </div>
   }
 
-  onLayerSelect = (layerId) => {
-    const idx = style.indexOfLayer(this.state.mapStyle.layers, layerId)
-    this.setState({ selectedLayerIndex: idx })
+  onLayerSelect = (index) => {
+    this.setState({ selectedLayerIndex: index })
   }
 
   setModal(modalName, value) {
diff --git a/src/components/MessagePanel.jsx b/src/components/MessagePanel.jsx
index f114a8c..105eeb3 100644
--- a/src/components/MessagePanel.jsx
+++ b/src/components/MessagePanel.jsx
@@ -1,5 +1,6 @@
 import React from 'react'
 import PropTypes from 'prop-types'
+import {formatLayerId} from './util/format';
 
 class MessagePanel extends React.Component {
   static propTypes = {
@@ -23,7 +24,7 @@ class MessagePanel extends React.Component {
         const layerId = mapStyle.layers[parsed.data.index].id;
         content = (
           <>
-            Layer <span>&apos;{layerId}&apos;</span>: {parsed.data.message}
+            Layer <span>{formatLayerId(layerId)}</span>: {parsed.data.message}
             {currentLayer.id !== layerId &&
               <>
                 &nbsp;&mdash;&nbsp;
diff --git a/src/components/inputs/StringInput.jsx b/src/components/inputs/StringInput.jsx
index c45e02c..5c6fa58 100644
--- a/src/components/inputs/StringInput.jsx
+++ b/src/components/inputs/StringInput.jsx
@@ -79,6 +79,11 @@ class StringInput extends React.Component {
           this.props.onChange(this.state.value);
         }
       },
+      onKeyDown: (e) => {
+        if (e.keyCode === 13) {
+          this.props.onChange(this.state.value);
+        }
+      },
       required: this.props.required,
     });
   }
diff --git a/src/components/layers/LayerEditor.jsx b/src/components/layers/LayerEditor.jsx
index 79b4c16..291cae2 100644
--- a/src/components/layers/LayerEditor.jsx
+++ b/src/components/layers/LayerEditor.jsx
@@ -107,7 +107,10 @@ export default class LayerEditor extends React.Component {
   }
 
   changeProperty(group, property, newValue) {
-    this.props.onLayerChanged(changeProperty(this.props.layer, group, property, newValue))
+    this.props.onLayerChanged(
+      this.props.layerIndex,
+      changeProperty(this.props.layer, group, property, newValue)
+    )
   }
 
   onGroupToggle(groupTitle, active) {
@@ -151,13 +154,16 @@ export default class LayerEditor extends React.Component {
           value={this.props.layer.id}
           wdKey="layer-editor.layer-id"
           error={errorData.id}
-          onChange={newId => this.props.onLayerIdChange(this.props.layer.id, newId)}
+          onChange={newId => this.props.onLayerIdChange(this.props.layerIndex, this.props.layer.id, newId)}
         />
         <LayerTypeBlock
           disabled={true}
           error={errorData.type}
           value={this.props.layer.type}
-          onChange={newType => this.props.onLayerChanged(changeType(this.props.layer, newType))}
+          onChange={newType => this.props.onLayerChanged(
+            this.props.layerIndex,
+            changeType(this.props.layer, newType)
+          )}
         />
         {this.props.layer.type !== 'background' && <LayerSourceBlock
           error={errorData.sources}
@@ -209,7 +215,12 @@ export default class LayerEditor extends React.Component {
       />
       case 'jsoneditor': return <JSONEditor
         layer={this.props.layer}
-        onChange={this.props.onLayerChanged}
+        onChange={(layer) => {
+          this.props.onLayerChanged(
+            this.props.layerIndex,
+            layer
+          );
+        }}
       />
     }
   }
@@ -242,15 +253,15 @@ export default class LayerEditor extends React.Component {
     const items = {
       delete: {
         text: "Delete",
-        handler: () => this.props.onLayerDestroy(this.props.layer.id)
+        handler: () => this.props.onLayerDestroy(this.props.layerIndex)
       },
       duplicate: {
         text: "Duplicate",
-        handler: () => this.props.onLayerCopy(this.props.layer.id)
+        handler: () => this.props.onLayerCopy(this.props.layerIndex)
       },
       hide: {
         text: (layout.visibility === "none") ? "Show" : "Hide",
-        handler: () => this.props.onLayerVisibilityToggle(this.props.layer.id)
+        handler: () => this.props.onLayerVisibilityToggle(this.props.layerIndex)
       },
       moveLayerUp: {
         text: "Move layer up",
diff --git a/src/components/layers/LayerList.jsx b/src/components/layers/LayerList.jsx
index 8d60bb4..12c4044 100644
--- a/src/components/layers/LayerList.jsx
+++ b/src/components/layers/LayerList.jsx
@@ -165,12 +165,15 @@ class LayerListContainer extends React.Component {
 
     const listItems = []
     let idx = 0
-    this.groupedLayers().forEach(layers => {
+    const layerIdCount = new Map();
+
+    const layersByGroup = this.groupedLayers();
+    layersByGroup.forEach(layers => {
       const groupPrefix = layerPrefix(layers[0].id)
       if(layers.length > 1) {
         const grp = <LayerListGroup
           data-wd-key={[groupPrefix, idx].join('-')}
-          key={[groupPrefix, idx].join('-')}
+          key={`group-${groupPrefix}`}
           title={groupPrefix}
           isActive={!this.isCollapsed(groupPrefix, idx) || idx === this.props.selectedLayerIndex}
           onActiveToggle={this.toggleLayerGroup.bind(this, groupPrefix, idx)}
@@ -189,6 +192,10 @@ class LayerListContainer extends React.Component {
           );
         });
 
+        layerIdCount.set(layer.id,
+          layerIdCount.has(layer.id) ? layerIdCount.get(layer.id) + 1 : 0
+        );
+        const key = `${layer.id}-${layerIdCount.get(layer.id)}`;
         const listItem = <LayerListItem
           className={classnames({
             'maputnik-layer-list-item-collapsed': layers.length > 1 && this.isCollapsed(groupPrefix, groupIdx) && idx !== this.props.selectedLayerIndex,
@@ -196,8 +203,9 @@ class LayerListContainer extends React.Component {
             'maputnik-layer-list-item--error': !!layerError
           })}
           index={idx}
-          key={layer.id}
+          key={key}
           layerId={layer.id}
+          layerIndex={idx}
           layerType={layer.type}
           visibility={(layer.layout || {}).visibility}
           isSelected={idx === this.props.selectedLayerIndex}
diff --git a/src/components/layers/LayerListItem.jsx b/src/components/layers/LayerListItem.jsx
index 0e9a238..7f1719e 100644
--- a/src/components/layers/LayerListItem.jsx
+++ b/src/components/layers/LayerListItem.jsx
@@ -62,6 +62,7 @@ class IconAction extends React.Component {
 
 class LayerListItem extends React.Component {
   static propTypes = {
+    layerIndex: PropTypes.number.isRequired,
     layerId: PropTypes.string.isRequired,
     layerType: PropTypes.string.isRequired,
     isSelected: PropTypes.bool,
@@ -97,7 +98,7 @@ class LayerListItem extends React.Component {
 
     return <li
       key={this.props.layerId}
-      onClick={e => this.props.onLayerSelect(this.props.layerId)}
+      onClick={e => this.props.onLayerSelect(this.props.layerIndex)}
       data-wd-key={"layer-list-item:"+this.props.layerId}
       className={classnames({
         "maputnik-layer-list-item": true,
@@ -110,20 +111,20 @@ class LayerListItem extends React.Component {
           wdKey={"layer-list-item:"+this.props.layerId+":delete"}
           action={'delete'}
           classBlockName="delete"
-          onClick={e => this.props.onLayerDestroy(this.props.layerId)}
+          onClick={e => this.props.onLayerDestroy(this.props.layerIndex)}
         />
         <IconAction
           wdKey={"layer-list-item:"+this.props.layerId+":copy"}
           action={'duplicate'}
           classBlockName="duplicate"
-          onClick={e => this.props.onLayerCopy(this.props.layerId)}
+          onClick={e => this.props.onLayerCopy(this.props.layerIndex)}
         />
         <IconAction
           wdKey={"layer-list-item:"+this.props.layerId+":toggle-visibility"}
           action={visibilityAction}
           classBlockName="visibility"
           classBlockModifier={visibilityAction}
-          onClick={e => this.props.onLayerVisibilityToggle(this.props.layerId)}
+          onClick={e => this.props.onLayerVisibilityToggle(this.props.layerIndex)}
         />
     </li>
   }