@e3fc6945 - great question!

"From what I heard, an antimatter blackhole is just a regular blackhole."

Nobody knows for sure.  Not only haven't we studied this experimentally, for obvious reasons, the theory is a bit murky.  General relativity hints that black holes formed from matter and antimatter are the same.  But as you note, this would allow us to violate various conservation laws - for example, we could use black holes and Hawking radiation to convert matter into antimatter in ways that are "illegal" in the Standard Model of particle physics.  

The problem is that nobody has combined general relativity and the Standard Model into a single theory that we believe in.  Until we do, it's hard to give a definitive answer to your question... and this question shows how challenging this task will be! 

 @b4c50e1b Oh thanks! I better understand the issue now 😊

As a non-physicist, it can be difficult to evaluate the certainty associated to a model, and I did not realise that I was probably using one outside the validitity of its assumptions. I guess that the huge amount of energy involved could have hinted that maybe things are more complicated than I imagined 😊 

 @b4c50e1b @e3fc6945 There is an example of this in Wikipedia. I'm not sure though if I believe if the no-hair conjecture applies to other quantum numbers. https://en.wikipedia.org/wiki/No-hair_theorem#Example 

 @b114a88b @e3fc6945 - the thing is, the no-hair theorem is proved using general relativity plus classical Maxwell theory or some other classical theory, so it has nothing to say about black hole evaporation.