We try to identify possible duplicate transactions based on dates and amounts. When we notice similar or almost identical transactions, we list them in Resolve Possible Duplicates under Troubleshooting in your Transactions dashboard. Click that link to view what we consider to be possible duplicates, and let us know which ones you want to Keep or Delete. If you're not sure at the moment, you can mark it as Unknown, but make sure to come back to it later.
We pick out possible duplicates by date, amount, and transaction title. It's possible that you may have just had two or more of the exact transaction in the same amount happen on the same day. In that case, mark all to Keep. Otherwise, Delete what shouldn't be there then click the Resolve Duplication button to keep your books in order!
TIP: If you've done your bank reconciliation for the same period as the possible duplicate transaction, AND you've verified that your ending balances (do this in Reports > General Ledger) match your bank's, that's a pretty good sign that all your transactions have been accounted for and that the transactions captured are not actually duplicates. Once you're confident about that, just tick Keep, then Resolve Duplication.