Adding a second, different tortoise?

I've got a redfoot tort, and am wanting to add a companion for him/her. I'd really like to bring in a yellowfoot, but haven't been able to find anything in the way of how they'll get along out there on the web. I have found reading material that mentions different immune systems and different parasites and/or bacteria, but it seems to point more to animals living in vastly different areas. Like redfoot and leopard.

Does anyone have experience having different torts live together? Or should I just get another redfoot if I want a pal for the little one I already have? I would of course be quarantining, and they both seem to have very similar care requirements. The new addition would ultimately be of similar size.

Tips and advice appreciated. I don't want to mess this up.

I've never housed reds and yellows together, but know that it's done and have run into a few hybrids over the years. From what I know, you want to make sure there is a shady humid place that the yellow can hide in. They are less resistant to heat than reds and live in the rainforest avoiding open fields and excessive exposure to the sun. Also be sure to quarantine the new one and make sure it is free of parasites, but it sounds like you know that. Do more research, but I know that it is not uncommon for the two species to live together.

I have kept both Redfoots and Yellowfoots over the years. Currently just Redfoots. While they both have similar care requirements, there are a few important differences. Generally speaking Redfoots like more heat and can tolerate a little less humidity. That is not to say that Redfoots don't need humidity, they do, lots of it! But they can tolerate occasional dryer periods than Yellowfoots if it should happen. Their diet is similar, as is their substrate and light needs. Redfoots barely bask under direct light and Yellowfoots even less so. Overall heat and humidity are more important to both species well being than a basking light. Some people suggest that a UVB source is necessary. Many experienced and successful Redfoots breeders disagree. I use a florescent light on mine only as a source of light and have had no health issues with them whatsoever.
The best addition for a Redfoot is probably another Redfoot. Mixing species is usually not a good idea because many species do have different care requirements, immunity levels and sometimes social and aggression levels. While Redfoots and Yellowfoots are similar, they are not the same and neither is the details of their care requirements. But if you are going to mix two species, Redfoots a Yellowfoot is going to be the closest to a Redfoot in terms of overall care requirements. Absolutely quarrantine a new tortoise. Wild caught Yellowfoots are notorious for bacterial and worm infestations. If purchasing a captive bred animal that shouldn't be a problem at all unless that tortoise has been kept with recent wild caught animals.

Thank you, the advice is appreciated. For now Terry is solo.