I tend to do that a lot. Bad habit, something I really shouldn't be doing. ^^;; But I can never really make up my mind to play just ONE, or even two different people. To be honest, whenever I make one, they tend to be very c.lose to Mary-Sue-ish, so I guess it's like my little sneaky way out of it.
That and I have a bad tendency to RP the same type of characters for a while (before it was Healers, then Super-Strength peeps, now siblings)