Im not sure if the information in this link is still true, but inblue tested it back in September 2018 http://wiki.biblepay.org/Multiple_Instances Id rather everyone know about it, than just a few
No - incorrect - this was posted in September 2017, back when we had V2 of POBH. Thats before we released Sanctuaries.
Thats why we have to prove this is no longer an exploit for miners since V3 of POBH (we are up to V14 now).