A material pose doesn't care what the figure names are - as long as they a) are figures*, b) have the same material names and c) have the same UV mapping then it will work without any special attention. You just apply the same pose to each shoe in turn. To make sure of b) and c), make one shoe and then mirror it. This also has the advantage that you only need to make morphs for one shoe, as well. Edited to add: *Prop shoes will work just as well, but you can only apply a pose to them while they're parented to a figure.