I'm a dancer. "Take it from the top" means to start a run through of the current piece from the beginning. Except … we were practicing a section of a piece. An

I'm a dancer. "Take it from the top" means to start a run through of the current piece from the beginning. Except … we were practicing a section of a piece. And then we started digging into the details on a very specific portion of footwork in the middle of that section. And our choreographer, instead of saying "start from the section", said, "start from the top". And humans being what they are, we all understood, somehow, and the right thing was done without complaint. But then came the need to start from the beginning, at which point she now had to differentiate from what she had been calling (erroneously) "top", and uttered "start from the top top". Some amount of playful joshing followed … and then the term stuck.