I have 2 corys in my 20gal planted tank. One is a black finned cory and the other is a false Juli. One was my first fish and survived through the "learning period". Now the tank is densely planted and I very rarely see them, so rarely that I often forget that they are in there . I had 6 at one point, but my school has dwindled over the years. I have no plans to get anymore to provide them with a proper school. Now would it be best to take them to a LFS or are they fine with just the 2 of them?
As long as you can provide them with a safe and healthy environment, I would suggest keeping them. Let them live out their days in the home they are used to. The idea that they might be separated and sold to different homes, perhaps to live alone, is a sad thought.