My two common(?) sailfin(?) plecos do fine in my pond. It is large enough and has two separate shelf/rock areas so they each have their own spot. When I bring them in for the winter, they seem to tolerate each other okay in the smaller tank (40 gallon breeder - yes I know it is too small for them, and I do water changes 2-4 times a week to keep
ammonia in check). There are the occasional squabbles over their favorite hiding spots, but they do pretty well. Usually one is on one side of the tank and the second is on the other. I feed them on both sides of the tank so there is no squabble over food.
As long as you have a large enough tank and sufficient hidey holes, they may be just fine. I think it also depends on if they are used to sharing their space or not. Mine were bought at the same time, from the same store, when they were only 1/2 inch long. They have never been separated for more than a few minutes (when I catch them to bring them in).