There have been times when the Yodlee credit card import didn't work and we went weeks, even months, with no credit card transactions showing up in FeNxt. When the transactions were finally imported, there were also a lot of duplicates (150+). The current and only way to remove duplicates is to go to Credit Card Activity, find the duplicate transaction, and click the 'Ignore' button.
However, if a duplicate transaction is edited and submitted, there's no way to remove or ignore the transaction. The only option is to 'Reject' the transaction or leave it with an 'Open' status. So there should be another way to remove/ignore duplicate transactions.