what do you call 2 routes at once? You mean the same day? Yes, the same day, a place can fly several routes. With very short distances, a regional jet(CRJ or ERJ, for example) can fly 5 times a day. It's even mandatory for surviving on the short routes market to fly all day long.
Or you mean they fly on the same route, at different times? Yes, possible also. in Current GW3, I've got 3 ERJ145 who each fly 5 times a day between Fuerteventura & Las Palmas. Opposition flies respectively 11 A320 and 10 A319 on the same line. That's a total of 36 flights a day between 3 companies and probably no more than 7 planes(though other companies can perfectly use their A320 on several different routes the same day, I'm doing it in other situations).
If you mean something else, please explain.