You can open a support ticket to request adding either first name or last name as an additional dedupe criteria. That means that if you upload a list with the following names:
Joe office@company.com
Beth office@company.com
Then 2 leads will be created. There are limitations though: if you send out a batch email, only 1 of the Leads will receive the email (otherwise you would have multiple identical emails in the same inbox). Also, there is a good chance that you will track the web behavior of a shared computer, and those web visits will all be linked to the record the filled out the form or clicked the link in the email. In your specific scenario, it may actually help though, because it sounds like it's event registrations with trigger email confirmations. Just be aware of the above mentioned limitations.