^ That, no offense, was extraordinarily inept.
A duel to the death between two sufficiently skilled Force users involves a lot moar factors than bench-pressing. Bench-pressing is fairly straightforward and fairly simple; duels require a complex series of actions, sequences, and movements -- and that's just with the lightsaber.
Vaapad didn't make Windu infallible in that match, the novelization and screenplay both depict him falling victim to a Force push, not to mention that it didn't stop his teammates from dying (if Windu's Vaapad was perfect, then he should have been able to annihilate Sidious with the assistance of the other Masters) nor did it prevent him from being driven back into the main office.
You can't automatically assume that circumstances would occur to allow Windu to defeat a more powerful adversary just because he managed to do so before.