I think it's less about being the same gender as being perceived as having a similar role in the narrative. For instance, Pulaski was explicitedly Crusher 2.0 as she was the replacement doctor, Data was a reworking of Spock, Riker was "Kirk" especially in the early seasons despite not being The Captain. On the other hand, despite doing a similar job on-screen, Ro mostly wasn't Wesley 2.0 as her role within the team was slightly different.