I accidentally imported a QIF twice and noticed too late. What can I do?

[Michel Albert]

I imported a file, but the importer did not gave me enough information to
properly assign the accounts. So I manually made these changes *after* the
import finished. I believe all these manual changes have triggered so many
backup files that they rolled over.

After my fixes, I realised I imported the same file twice.

Now I have a /huge/ number of duplicates.

Is there any way to search for duplicates? They all are in the same
account, with the same date and same amount. I might be able to scratch out
a backup from somewhere, but that might be *old*. So I'd prefer to use a
more "automatic" procedure if somehow possible ;)