Patrick, what is the effect on anonymity if one was to attack two workstations via 2 different internal networks/ internal facing NICs on the same Whonix Gateway?
Which machine is the compromised one, which one is the attacker?
Maybe this is related.
Please tell me any further questions! 
Very helpful links thanks.
One more question: Would anonymized traffic coming from an exit note indicate that the output of both machine (on their separate and secure virtual networks) is coming from the same entity?
I’ll ask about the other question and post the answer. So others can find the answer later.
How about the last question I posted in this topic?
The answer was in your excellent wiki all along!
Multiple Whonix-Workstations (using different internal IP's) are automatically separated by Tor (IsolateClientAddr is Tor's default).