Many couples, especially older couples, share one email address. During a weekly COVID press conference led by Vermont Governor Phil Scott, a reporter asked about a reader who had complained that a couple was unable to register both of them for a vaccination appointment, because they didn't have separate email addresses, one for each of them.
The speakers were not sure if this was a real issue, and planned to investigate.
A workaround is to telephone for an appointment rather than using the web appointment system.
At the time the question was asked (February 2, 2021) appointments were available to those 75 years old and above.