Duplicate citation key

I have two papers in my library with the same BibTeX citation key. Both have the same first author and publication year, but the additional two-character suffix at the end of their keys is the same (both “Olson2014-gz”). This is causing me problems when I try to use the exported .bib file with other software.

Hmm, we would have to investigate how this has occurred. The fix, however, is fairly simple: use the edit box to edit the citation key manually. You may have to use the “Additional fields” button at the bottom to reveal the citation key field.

I also have this problem. By chance I found 2 papers with the same BibTeX key, I changed one of them as recommended (BTW, if I delete the key and let Paperpile generate a new one, it will still generate a duplicate key). The edited reference is correctly found if I search for the new key, however it is also retrieved if I search for the old key. Is there somewhere else where the BibTeX key is stored that I need to edit?