Don't think so, the unwrap modifier will probably have a check against creating degenerate faces (degenerate faces are those where one vert is used repeatedly, such as the top/bottom 2-vert faces of max teapot).
Removing the channel there would be no map verts at all. I'm curious about one map vert for all map faces, could it be done without building the mesh via maxscript ? All faces having the same vert index ?
I think it happened once to me, but the mesh wasn't mine and i have no idea how to reproduce it. People always come with the weirdest bugs. The uv's of duplicated elements were welded together. I don't remember if i checked it, but i guess then the map verts were fewer than geo verts. Unwanted behavior anyway. I had to…