that 2 frames overlapping each other is actually a technique to make the animation feels more smoother, because it will make the transition of each frame more blurry in our mind. another example you can find here is the drop the koakuma.
and no, breasts isn't overlapped by another breast frame on it's "normal position". if you see the last frame, yes they're overlaping. but on the initial frame, it's not overlapped by another breast frame and this one is the proper "normal position".
that 2 frames overlapping each other is actually a technique to make the animation feels more smoother, because it will make the transition of each frame more blurry in our mind. another example you can find here is the drop the koakuma.
and no, breasts isn't overlapped by another breast frame on it's "normal position". if you see the last frame, yes they're overlaping. but on the initial frame, it's not overlapped by another breast frame and this one is the proper "normal position".