+1. While not ideal, I have personally had it work out when I had to consolidate my tanks due to power outage after being hit by 3 hurricanes.
I would not recommend it in a smaller tank as it would most likely result in bloodshed but in a large enough tank with plenty of rock work, both fish should have room to establish their own territory. Of course, some fish are just naturally more territorial than others so it is a case by case situation.
Right now I have two lawnmowers in my 75 purely by accident. I thought the first one was dead, as I hadn't seen it in quite a while and bought another. Now, I see both perching on opposite sides of the tank. Oddly, one of them actually perches on my lta from time to time. Even at feeding time, they feed together, seemingly oblivious, then go back to their "space".