collision

Definition

In cryptography and identity collision generally refers to something going wrong because an identical result has been produced but it refers to - or points to - different sources or assets backing this result.

E.g. two hashes collide, meaning two different digital sources produce the same hash.
Another example is name(space) collision.

Naming collision

A circumstance where two or more identifiers in a given namespace or a given scope cannot be unambiguously resolved.
Source Wikipedia