Mine used to be 2 grids high which was easier for me to clean. Now its only one grid high and I find it much harder to clean as it hurts my back because I have to bend too low. I think I may have to make it higher as I'm worried about putting my back out completely. I guess it depends on your height. I'm 5'6" but if someone was 5'2" a one grid stand would probably be better.
If your cage is a single story cage then a stand 2 grids high is ok. If it's multistory, then you want 1 grid high stands.
I have stacked cages at the moment. A 2x4 with a 2x3 above. They sit on a piece of plywood on top of grid stands 2 grids high. I can only reach the front corner of the upper cage without either having a step-ladder or pulling the tray out.