You should probably keep them separated for a little while, or at least until you know for sure that the new gecko isn't sick. When your ready to introduce them again, I've been told to introduce them by letting them see each other thru glass at first.
Hello, my name is donnaranee33 and I'm new to gecko talk. Looking to meet some new people and have great conversations. I currently have 1 bearded dragon, 1 leopard gecko, 1 crested gecko, 1 russian tortoise, and 1 kenyan sand boa.