If it was me.. I'd split it evenly so I wouldn't have to switch them around every week or so... it's more work for you but if it's permenant... I'd do it!
There are 2 doors right? A large one on top and smaller one on bottom? If it was split in the middle, you'd only have to open the large door to feed both chinnies... the only problem would be if you have escape artists then you'd have to watch that one doesn't bolt on you... though you probably would have that same problem already with them in the same cage..
OK, I'm just rambling now...
