Possible duplicates

Sending exactly the same file again is an exact duplicate. It uses no scan, because there is nothing new to read.

Two documents are likely duplicates when their images are nearly the same, or when they have the same merchant with the same total within a cent and three days. Two receipts with different receipt numbers are never treated as duplicates.

A likely duplicate waits under Review. Choose Keep all if they are both real, or Keep one and void the rest. A voided expense stays on record and leaves every total.

Someone who manages settings can change these limits under Settings, General, in the Documents section, within safe bounds.