Address adapter unload existing record on create.

address_adapter.js

import Ember from 'ember';
import ApplicationAdapter from 'adapters/application';

const {RSVP, run} = Ember;

export default ApplicationAdapter.extend({

  //unloads existing record if create record returns a duplcate.
  createRecord(store, type, snapshot) {
    let saving = this._super(store, type, snapshot);

    return new RSVP.Promise(
      (resolve, reject) => {
        saving.then(
          (payload) => {
            let id = payload.address.id;
            let existing = store.peekRecord('address', id);
            if (existing) {
              store.unloadRecord(existing);
              run.next(() => { resolve(payload) });
            } else {
              resolve(payload);
            }
          },
          (error) => {
            reject(error)
          }
        );
      }
    );
  },
});

The run.next is not needed per this thread. You should use run.schedule('destroy', () => resolve(payload)) instead.