Hi craig,
You don't need to overwrite your data, and we can't do that either. Instead, you can undo the transactions from the Banking page to remove them from your books.
Duplicates caused by bank transactions often occur when users add transactions instead of matching them. To fix this, simply undo the added transactions to bring them back to the For review section. From there, you can match them to their corresponding transactions in your books.
Feel feel free to go back to this thread if you have other questions in mind.
