I recently submitted a resume which went directly to the hiring manager. He asked me for an interview the next day and I agreed. At the end of the interview, I received his contact information and he asked me to attend a second interview with another manager the following day. This process has taken part over 3 days so far.
My question is do I only follow up with the first manager that I saw on the second day as the thought of sending two thank-you emails within 24 hours seems a bit like a spam. Or alternatively do I send a single follow up email that addresses them both?