CheckBook does run some checks to see if the transaction in the new QIF already exists in your account. If it matches, the incoming entry of that QIF will be unchecked on import and will not come into the account. It is a pretty narrow set of criteria, because we do not want to miss importing a transaction that is of the same amount in the same time span.
If you have specific examples and would like to discuss this further, feel free to post examples or email us more details on how you expect these features to work. You can always reach us at
support@splasm.com