Yes, it will send two emails to the one address, one email for each spouse. If the client has their email reader set to "thread" emails, they do thread on top of each other, so the client may not immediately recognize there are actually two.

Each return uses one e-signature instance, for every scenario I've encountered. Single filers, joint filers, spouses share an email, spouses have separate e-mails, package has to be voided and re-issued.