I'm sorry but the "cats are solitary creatures" is a load of bull IMO.
Was born into a multiple cat household and had multiple cats in my own home (all unwanted).
Each cat was different, just like humans.
Some wanted to be around other cats or people, some didn't.
I used to come home to a pile of cats all asleep on each other on my bed (including a couple that didn't even belong to me but one of my cats used to like bringing friends home!)
The only time we lost one of our cats under the age of 10 was either due to being hit by a car or cancer or other illness outside our control.
All the rest lived well over 17 years (some were 20-22 when we lost them) despite having lived with loads of other moggies.
My current cat is nearly 19 and lived her whole life with loads of cats of various ages and breeds. She's had a vet check up a few months ago and apart from being old she is fine.
Recent studies carried out on feral cat colonies (that all live together) found that mum cats will give birth together and help raise each other kittens.
Just be prepared for the double costs (and some buggers may not like the same food as the other one.... bloody gits!) and double the trouble but double the cuddles and fun :)