One arm dislocate vs two

Why is my ROM greater when I only do a dislocate on one side vs doing a dislocate with both arms at the same time?

When using both arms, your torso can't rotate. 

My guess is simply that holding onto a bar with two hands forces you to move through the whole ROM with a constant width. Whereas with a single arm you can cheat slightly, even if it's so subtle you don't really notice. With one arm you can get a tighter circle through most of the movement, but you can also easily get past the tricky two-hand dislocate sticking points.

 

For example my ROM on HS/PE1/PE3-iM is shoulder width, but the transfer between those two is where I lock up. Doing it with one arm seems like a tighter circle, but it isn't where it really counts.

Yeah, they don't begin to compare.

Good as general loosening up shoulders, but then you may as well xiaopeng and get a bit more out of it