Let's say that Alice and Bob complete a key exchange and then Alice uses that key
k1 to encrypt a 256-bit key
kaes1 and sends it to Bob. From there, Alice and Bob exchange a lot of messages back and forth, using AES-256 to symmetrically encrypt the data with the key
Then, Charlie comes along and wants to participate, so Alice and Charlie complete a key exchange and Alice then uses that key
k2 to encrypt the same original
kaes1 and sends it over to Charlie. From there, Alice and Bob and Charlie now exchange a bunch of messages symmetrically encrypted with AES-256.
Eve has been listening in this whole time, and she has all the data, but none of the keys. Does Eve gain an advantage if she knows that kaes1 was the payload for 2 different messages encrypted with 2 different keys