Does weld do what I think it does?

Hi All,

So I’ve made a model of a dumpster. I made heavy use of the Mirror modifier, but at the end I had to apply the modifier in order to combine all of my components into a single object. I end up with the following model and UV layout:

This looks good, but because I used the mirror modifier so much it seems as though I have far more UV vertices than I thought:

To fix this I box selected my island and pressed Remove Doubles UV

Whenever I do this it looks as though nearby vertices get piled atop one another. However, I can easily replicate the second picture, which implies that the vertices/islands are not really being merged into one (I think). Similarly, if I weld all vertices and end up with one single vertex, I can still move it around to reveal many more underneath.

My goal here is to minimize the amount of texture coordinates I need to store; I will be exporting this to a .obj file, and if there are redundancies in the data it will be bad for everyone. Basically I’d like all faces associated with those islands to share UV data.

For the record I tried this with a cube and did get it to work (as in, it seems as though I was able to end up with one island.) Is there something wrong with this configuration/model that could result in the operation not succeeding? I don’t see any error messages.

Thanks for your help.