Not as easy to answer
as it may seem. If two heretofore simultaneous failure proof systems have just failed, and not due to all the engineered in safety of ETOPS, then the answer is no, twelve engines would have failed the same way. Isolation from bowser to chox is possible (At ridiculous cost), so by definition we're dealing with a non Etops issue.
My mentor and his co-pilot ate the same pork sandwiches on their way to bomb Tokyo in 1945. Both got food poisoning and were unable to fly. The chicken sandwich got ate by the navigator, who was an eager ab initio student on the way back. Separate everything for each side on the ETOPS twin? Ouch, you think Fuel's expensive.....
Airfoil