Do you know that this cycle I had the exact same thing happen, ++ opk at CD 14-15, then positive again at CD 21-22. The first time I had a temp rise but it didn't stay, the second time nothing really happened..
You on the other hand had a very nice temp shift that was sustained, so you had a clear ovulation. So weird your OPK is positive again..possibly from hcg? Not saying for sure, but it might be!