Thanks. That’s definitely the best one. Googling the problem (which of course I should have done before posting) also reveals herd, horde, and colony.
Now, regarding the OP, does (do?–I’m in uncharted grammar waters here) two mice make a mischief?
No, they’re pretty well behaved.
(Although now we’ve got different problems. Roommate just found out that she won’t be allowed to bring her mice with her on the plane when she goes on Passover break. She’d like me to look after them for the week. I have two cats. Yeah).
Sorry, don’t mean to beat a dead, tagged, glowing mouse but this is brilliant! I should start on the T-shirt graphic.
Well, that’ll take care of the mouse identification problem, at least. “Mice? What mice? [purrrr…]”
Then when your roommate replaces the mice she can get ones that she can tell apart.
I should warn you guys that you made Roommate cry with your “cut off their tails” jokes. She may have a nervous breakdown from reading Kimstu’s post.
Oh well, on the other hand, the cats will be happy. Can’t please everybody. 
[Dear Malleus’s Roommate, we are just kidding and sincerely hope your beloved Sophie and Alba will lead long and happy lives even if one of them is a funny color. Love, The Straight Dope Message Board]
Just dunk them in the contents of several broken light sticks…
It’s been done. Sort of.
I’ve had hamsters and cats at the same time. The cats have always watched over the hamsters intently. The trick is to not let the rodents run around the place freely, as the cats think that this is a great opportunity to practice their pouncing. Instead, get one of those plastic ball thingies. Insert rodent, close ball, let rodent run around the place. Watch rodent run the ball up to the cats. Enjoy the look of frustration on the cats’ faces. Watch cats jump up on chairs, to get away from the nasty, nasty rodent.
I had one of these balls with my first mouse… he used to chase the dog in it. It was one of the most entertaining things ever.
I want to get a mouse/hamster and a rodent ball now.
PlainJane, I’ll take one of those t-shirts when you start production. 
I want to get and rodent ball AND a cat, now! And I already have a parakeet! Hey, maybe he would like to get in the ball and chase a cat!
Heh - cool video. The complex display bits are pretty obviously fake, but they clearly went to a lot of bother with the whole setup - I like it.
You could always get a mean dog to make sure the cats don’t get out of line.
My sister brought her rats over one holiday. We had a kitten. They actually played together nicely (or at least with no bloodshed), although admittedly we were watching very intently and it was probably for less than a half hour. And at the time, the cat wasn’t that much bigger than the rats. (My parents have pictures. Unfortunately I don’t.)
Like my grand daughter, fer example. 
This query made two pages, so far?
There is hope for the world.
Although the subject of tattoos has come up and dismissed, e.g. my rice-sized transmitter idea was greeted with a deafening silence, I have found an even better method that dispenses w/ the need for a transponder:
Use LED tattoos. Either write their individual names, or just one, Sophie, say, and figure that the other must be named Alba. The LEDs move when they are stroked, for good measure.
They already are used in mice.