duplicateItemsAllowed option is now respected by setChoices() met…

…hod. Resolves #855

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Features (from 11.0.0)
 * Pass `getClassNames` as the 3rd argument to `callbackOnCreateTemplates` callback
+* `duplicateItemsAllowed` option is now respected by `setChoices()` method [#855](https://github.com/Choices-js/Choices/issues/855)
 
 ### Bug Fixes (from 11.0.0)
 * Fix choice disable state wasn't considered when showing the "no choices to choose from" notice

src/scripts/choices.ts

@@ -2078,12 +2078,20 @@ class Choices {
       throw new TypeError('Can not re-add a choice which has already been added');
     }
 
+    const { config } = this;
+    if (
+      (this._isSelectElement || !config.duplicateItemsAllowed) &&
+      this._store.choices.find((c) => config.valueComparer(c.value, choice.value))
+    ) {
+      return;
+    }
+
     // Generate unique id, in-place update is required so chaining _addItem works as expected
     this._lastAddedChoiceId++;
     choice.id = this._lastAddedChoiceId;
     choice.elementId = `${this._baseId}-${this._idNames.itemChoice}-${choice.id}`;
 
-    const { prependValue, appendValue } = this.config;
+    const { prependValue, appendValue } = config;
     if (prependValue) {
       choice.value = prependValue + choice.value;
     }