You can achieve 100% engine correlation pretty easily. It just requires an unworthy opponent and we're talking very weak. Which engine is evaluating even matters, stockfish might say 100% but leela might say 95% because it saw some odd deep computer line you didn't play.
For a super gm to achieve 100% engine against another supergm? That's really telling there was an engine involved, in fact the same engine.
For a super gm to achieve 100% engine against another supergm? That's really telling there was an engine involved, in fact the same engine.