I'm sorry that I can't help you on that particular type of turtle. What you'll need to know is whether both species require the same habitat or not. If they aren't the same then you shouldn't keep them together. Check out this site:
Care Sheet
Now, what's your set up that you currently have? Anytime you are considering adding another turtle to your habitat, whether it's another RES or a compatible turtle of another species, you must ask yourself a few questions.
1) Will you be able to provide them with proper housing when they are full grown? A mature RES will be between 9-12 inches and require up to a 120 gallon tank/habitat when full grown. This is just for
one. If you add another turtle to the picture then this habitat must double.
2) Will you be able to afford to have two complete setups with all necessary equipment when they are grown? Even if two turtles get along now in the same habitat, this doesn't insure that they will when they get older. If they aren't compatible then you will have to provide each their own habitat.
3)Also remember that upon the purchase of any other turtle, you will have to keep it under quarantine for 90 days in it's own setup(w/proper equipment) to insure the health of your other turtle and make sure that the new turtle will not pass on any disease that it may have.
You have to think things out thoroughly before rushing into them with these type of pets. Their habitats require time, attention and money to make sure they are healthy and happy.
