This is one of the most common phenomenons I've heard ever since I started my research on the median system due to me experiencing it (yes, we do research before evaluation). A lot of pages and sources have been telling their experiences about this and I am no stranger to this either.
Before explaining i just want to emphasize that this is my personal experience, this can be different for every other system out there and it's fine, everyone experiences stuff differently.
In our case, the identity overlap is not a daily occurrence but is still very common, so common in fact we had to make a new proxy on Pk bot because of this. Taking an example for this, Wil has been lately one of the most common one to overlap with me. A list of characteristic to this phenomenon goes like this:
These are a few of the changes I can think of off the top of my head that we’ve noticed when this happens.