diff --git a/src/operations.js b/src/operations.js
index b0bcd9e..aeb79e0 100644
--- a/src/operations.js
+++ b/src/operations.js
@@ -1,6 +1,4 @@
-import first from 'lodash/first'
-import initial from 'lodash/initial'
-import last from 'lodash/last'
+import { first, initial, last, pickBy } from 'lodash-es'
 import { getIn } from './utils/immutabilityHelpers'
 import { compileJSONPointer } from './utils/jsonPointer'
 import { findUniqueName } from './utils/stringUtils'
@@ -149,13 +147,18 @@ export function replace (json, paths, values, nextKeys) {  // TODO: find a bette
     ]
   }
   else { // parent is Object
+    // if we're going to replace an existing object with key "a" with a new
+    // key "a", we must not create a new unique name "a (copy)".
+    const removeKeys = new Set(paths.map(path => last(path)))
+    const parentWithoutRemovedKeys = pickBy(parent, (value, key) => !removeKeys.has(key))
+
     return [
       // remove operations
       ...removeAll(paths),
 
       // insert operations
       ...values.map(entry => {
-        const newProp = findUniqueName(entry.key, parent)
+        const newProp = findUniqueName(entry.key, parentWithoutRemovedKeys)
         return {
           op: 'add',
           path: compileJSONPointer(parentPath.concat(newProp)),
diff --git a/src/utils/updateProps.js b/src/utils/updateProps.js
index 87e2d25..369d10f 100644
--- a/src/utils/updateProps.js
+++ b/src/utils/updateProps.js
@@ -78,17 +78,21 @@ export function patchProps (state, operations) {
     }
 
     if (operation.op === 'add') {
-      const path = parseJSONPointer(operation.path)
-      const parentPath = initial(path)
+      const pathTo = parseJSONPointer(operation.path)
+      const parentPath = initial(pathTo)
+      const key = last(pathTo)
       const props = getIn(updatedState, parentPath.concat(STATE_PROPS))
       if (props) {
-        const newProp = {
-          id: uniqueId(),
-          key: last(path)
-        }
-        const updatedProps = insertAt(props, [props.length], newProp)
+        const index = props.findIndex(item => item.key === key)
+        if (index === -1) {
+          const newProp = {
+            id: uniqueId(),
+            key
+          }
+          const updatedProps = insertAt(props, [props.length], newProp)
 
-        updatedState = setIn(updatedState, parentPath.concat([STATE_PROPS]), updatedProps)
+          updatedState = setIn(updatedState, parentPath.concat([STATE_PROPS]), updatedProps)
+        }
       }
     }
   })