it has been suggested to WGT though, to be able to break up the iron set. Like some people would dump their 3 iron for a hybrid or swap out a pw for a fourth wedge of another kind or for those who haven'e figured out the R11 8 iron, slap an 8 iron from another set in there.
It has never been commented on by WGT as to whether or not they would ever implement this. Me thinks not but one never knows. For now you are stuck with your entire iron set