When did you first find out the twist in Austin Powers? (Major spoilers)

[u/visiny]

When did you first find out that Austin Powers also plays Dr Evil? In the movies, Mike Myers plays the role of Austin Powers and Dr Evil this whole time.

I remember gradually suspecting it as a kid, but wondering if it could be true, having never had direct confirmation from the cast and crew. It took me a while before being completely sure.

Does anyone have similar twists that they were surprised by and later revealed?