same here, we ger ornates and sens in, they thought they had a congicus, were selling it for 69.99 and it was a sen that was a bit more of a brown (but barely, I have bigger shade diff in my tank because some live up top and some live near the bottom) than the others.
Anyways, I put a couple 4" albino sens in with my 10" ornate, 8" and some big sens that I wasn't worred about at all, the ornates though.... It worked out alright, the albinos have got to a decent size I'm not worried, but I did spend a few hours in front of the tank watching or any signs or aggression or hunger, they were fine. I also threw extra food in the tank 2 times a day so they were too fat to even fit one in, or even care. Also kept live feeders for about a week or two just to keep any thoughts of cannibalism at bay.
I also rearranged the tank and cleaned it really well to be sure any territory issues were reduced, made sure there were new places to hang out and some that were too small for the ornate to get into, just so they could hide out