Is "diagram too small" bug on multiple different diagrams considered duplicates?

[EvitanRelta]

Or is it because "fixing 1 doesn't fix another", so they aren't duplicates?

[damithc]

Or is it because "fixing 1 doesn't fix another", so they aren't duplicates?

Yes, they are not duplicates. If there is a high number e.g., 5+, you can request permission to combine them, but with a higher severity.