Post slug redirection problem after merging sites

I have merged two sites and having trouble. Some posts that were imported have added a -2 to the end of the slug. When I try to remove the -2 it reverts. The correct URL redirects to the -2 URL. The correct URL is NOT being used elsewhere.

I tried digging around in wp_postmeta but couldn't see anything applicable. I do have the redirection plugin on, but can't see anything in there either. (It seems to have lost some data, so…)

Any ideas on how to fix this? Here is the correct URL:

P.S. The subject line limitation is really odd. First not enough detail, then too much, then not enough. What?