Cannot create more than one 3rd party macro in the new editor

Summary

In the new editor (blog page) is not possible to insert more than one live macro in a page.

The Balsamiq add-on uses a custom editor. No live macro is inserted when the submit button (i.e. dialog.getButton("submit")) is clicked.

Steps to Reproduce

1. Create two macros (tested using Balsamiq Wireframes)
   Steps to reproduce video: http://recordit.co/5zwQAfbAmj

Expected Results

A new macro is inserted in the page

Actual Results

The second macro is not inserted in the page