Avoid UV auto merge when uv island is very near to each other.

I realized once an edge of a UV island is virtually near it or ontop of each other, Blender auto merges their seams. However this does cause confusion when it's intentional to have multiple shells overlapping each other, but when being investigated by moving them around, they seem to be one with each other.

As a by product, trying to split the UVs in edge mode doesn't properly split the shell as expected so instead I have to select the shell that I want to split apart for it to work. I've also realize when testing on this, if I split the shell and then deselect it and then reselect the same shell, it auto merges the split I had done again. Making me to assume this is some auto merge effect that Blender had done. To me this effect is really uncomfortable not knowing what is split or merged uv edges.