Removing Original Tag

[Aidan]

I had a few problem ebooks (originally from PDF) that I was trying to improve and convert to Mobi to read on my kindle. When I'd finished the various conversions and deletions I had one mobi file per book but some of them are called original_mobi from the conversions that didn't work properly. Is there any way to make any original_mobi format change to mobi if there is only one amazon format for the ebook? It might be a small problem but it's annoying my perfectionist side.