I've noticed since I began using PPro CC that the UNDO command works differently when 3 point editing. If i overlay a clip from the Source window onto a timelene, then decide I didn't want to do that, instead of undo-ing the overlay, the command goes back to my previous source clip in the source window. I have to manually delete the clip from the timeline. Anyone else experiencing this/ have a fix?
I'm not able to repro any such issue in PPro CC, but there are several variable at play that could affect the behavior. Perhaps if you fill in a few blanks:
When you perform the Overwrite, what does the History panel show?
Also, was the project started in CS6 and imported into CC?