Well, there's kind of a magical amount of floor space in a ten gallon. If you go much smaller, even 2 ASFs can be cramped. Cramping them can result in chewing issues, and agression.

I have some ASFs that are kept in 5 gallon tanks, but they are in pet colonies, with 3 female mice also. I feel like if there were another ASF in there, it would be too too too cramped. 1.1 -might- fit, but 1.2 would be really tight, to me.