I'm trying to perfectly overlap two images, one complementary of the other, but apperas a white stripe in the conjunction of the path, all points are perfectly aligned how can I fix?
One thing you can do to avoid this, is just Copy and paste another layer of both the objects. Try it I think it will solve your problem.
Well, just as joojaa said, this is a rasterization error, officialy there's not much that you can do about it but whenever I encounter this error, when the design and my time allows it I use the Direct Selection to select some points and the keyboard arrows to move them just a little to overlap the other image.
Another thing I do when I'm in a hurry, say for your design, Copy and Paste in place both objects, Unite them and send them to the back. See the difference: