Editing an unscheduled mailing after Save & Continue creates a duplicate mailing record

I suspect this might be related to the approval workflow changes, but not sure. The bug does NOT recreate in 3.3.5.

Steps to recreate:

• Create a new mailing and click Save & Continue on step 1
• Click "Continue" to edit that mailing, and now click Save & Continue after completing step 3 (might happen earlier, but didn't test that)
  You will see 2 copies of the mailing in the Unscheduled selector. Each time you "Save & Continue" we create another copy.