When photographing cats you must realize this: Cats don't pose, stay in one spot or follow any directions. The only thing I can do is place some props on a table and hope that the cat's natural curiosity will (if I just keep clicking away) get them into the same frame, facing in the general direction of the camera lens.
I've given up trying to get both cats in the same photo. If they do happen to both jump up onto the table at the same time, a hissing/slapping fit ensues and one (or both) will jump down. And then there's the lighting issue. Enough light (I use two Alien Bees) to properly light Beau's fur will blow out Sofia's white coat, leaving no furry detail whatsoever.
I think the last time I caught them in a photo together was in 2008 and it wasn't a studio shot. I had left a basket on my bed and came back to find this:
"Say 'Tuna Fish!'"