No, OOTB feature is not overwrite. This is responsibility of custom code you are developing but as per your comment you are saying it is sending both.
From what I am understanding below are the steps in your case.
- User requests E1, he gets E1.
- Same user requests E2 and IdentityNow is sending E1 and E2 both in plan.
If this is what you are seeing then it should not happen. I do not think this would ever happen because this is platform behavior and it never goes wrong. It’s just you are mistaken somewhere. You need to contact support to have more discussion or ES as per your requirement.