Flatfile aggregation

I have an flatfile based application say “App1” and it has 3 entitlements in entitlement catalog. (ent1,ent2,ent3)
When I run account aggregation for this App1, the file has 4 different entitlements for a user in the source file(ent1, ent2, ent3, ent4), the identity cube for this user is showing 4 entitlements but I was expecting only 3 to be in the users identity entitlement list.

please help me understand how to go about not aggregating that one ent’ whichi is not in the entitlement catalog for this app.

Thank You.