i rarely weld. it either doesn't weld enough vertices, or it welds too many. instead i use vertex-stitching. you never end up welding too many vertices, although sometimes, the damn thing will decide welding a certain pair of vertices is not a good idea.
practical not, but technical its correct that it is at least possible (because texture Verts and Mesh Verts are seperate arrays). I know that in UV-Layout from headus you can also only stitch sharing edges or vertices which saves a lot of time because in the past I often stitched texture vertices together that don't belong…