openzeppelin-subgraphs: Duplicate key value violates unique constraint after #25

Description

After #25, some entities were moved to immutable: true, which is reasonable and shouldn’t be a problem. However, there are some entities that are being saved twice (with the same data), so there was no issue previous to the migration to immutable, but now it flags them as duplicated.

Overall, this issue is not happening to all of the immutable entities, but here are some examples

Proposed solution

Just check that any immutable entity that already exists doesn’t get saved again.