Thanks for the help kurt.

But the problem still persist. I've not extruded the faces, I've duplicated them.

How can I put the vertices merged??

I've tryed put , when I duplicate the faces, the option "separate duplicated faces" off, and what happens is that, maya considerate the duplicated faces and the object (the object that I've dupicated the faces) the same object.

Thanks for the help kurt

Gamester