Thank you! I've been manually merging but will need to get the batch merge thing setup. One other question - is there a reason the records didn't sync up in Marketo when I uploaded my list? Wouldn't the system read the email address and know to sync to the other email address already in the system?
Yes, generally that would be the case.
Marketo will dedupe based on the email address and update that record accordingly. However, the question is, does your Marketo instance have a custom dedupe rule for List Imports (I would check with Marketo Support).
For example, a custom dedupe rule would be something like Email Address + First Name + Last Name OR Email Address + "Custom Field 1" etc. Hence since you only imported the list with email address + additional data, maybe it forcefully created new records.
If you do not have custom dedupe rules, I would suggest getting Marketo support to help with looking into your instance and identifying if there were any other reasons.
Hope this helps