We recommend the following best practices to reduce the chance of creating duplicate expenses from the card feed:
As a rule of thumb, do not push receipts to QuickBooks if they do not have a matching card transaction. This often leads to duplicates if either 1) someone later creates another receipt from the actual card transaction or 2) someone already created a receipt for that transaction that did match and pushed it to QuickBooks.
Use Adaptive cards. This will ensure card transactions are pulled into Adaptive immediately and matched (rather than the typical several day wait from other linked cards). This will greatly reduce the chance that you inadvertently create a duplicate.
If you must push a receipt to QuickBooks without a matching card transaction, be sure it is for a card that is not linked to Adaptive (and therefore will never be added to the card feed).