Thank you for your question. The symptoms that you are describing are consistent with an upper respiratory infection
. These infections are usually caused by viruses and in most cats will run their course in a week or two. My own youngest cat had quite bloody discharge when he was little for a few days--this is due to the inflammation in the nasal cavity.
If they are eating and drinking well, acting normally and playful, then you are safe to monitor them for a few days. If either of them becomes lethargic, stops eating/drinking, or seems to be running a fever, you should consider having them seen as antibiotics may be needed to help them overcome the infection.
In the meantime, some things that can help are keeping the nose and eyes clean (gently wipe away any discharge with a warm, moist cloth). Keep them well hydrated by adding water to any food
you are already feeding. Steam can also help. If the appetite seems slightly decreased, it may be from congestion and sometimes warming the food can help, just make sure it is not too hot.
I hope this information is helpful, please let me know if I can clarify anything or if you have any additional questions!