You could just generalize it as "Correspondence with Jessica Max Stein and Pam Arciero" in your reference, or you could be specific if you have a record of it.
(e.g. Email correspondence from [X] to [your name], [date])
“I've recently been cast as Ernie(!) However, when the new Sesame shows begin airing this fall, it'll be Billy's Ernie you'll be seeing. So far, I've only done the Chrysler spots, but I'm excited to be doing more!”
Hi Joe. We had previously discussed the topic of noting background puppeteers for major characters in things like the Sesame Workshop gala on this thread. Feel free to add your thoughts to the thread if you'd like, but in the case of character pages, noting one-time puppeteers when it's only a background performance isn't as essential as noting a speaking part or a recast. Thanks!