In the material editor when you load a bitmap file you have the possibility to make that image tile (1,0/1,0 as default). But what if you want to use that image several times with different tile? Well you can't. You have to load it in another bitmap map and change the tile... 2 loads for the same map.
As there's already a "tiles" map in the material editor, maybe it'd be a good idea to add that tile option in the "output map" node?