Basically, I’ve got excel lists of registrants for a serires of online webinars and we’d like to see how many people have registered for more than one event using the email addresses as the unique identifier.

The columns are first name, last name, email address, and registration time.

I had initally been adding a column titled “Repeat?” and after sorting by email, manually added a “1” next to the first instance of a repeat email address then summed that column to get a count of how many people repeatedly registered.

That method is both subject to human error and too time consuming to be sustainable as we approach 1,000 entries.

Any solutions are welcome!