No, You can assign multiple groups the same material but you can't assign materials to 2 polygons of one group and two polygons of another group without creating a whole new group with those four polygons. The reason is you can't select polygons from another group without inadvertantly adding those two polygons to the group you're working on. 

The grouping tool will only work on one group at a time. When you select polygons from another group, what you're doing is adding them to the current group and removing them from their previous group. This isn't something you want to do with Poseable figures.