I want to deduplicate a list of people in Marketo using the SFDC Account ID. This isn't possible using the Marketo Duplicate Fields filter. Does anyone know of a good workaround?
Export to spreadsheet, dedupe, and reimport is going to be the sanest approach. (I'm assuming you aren't/don't have a developer, though for a one-off the API isn't much better here.)
Sorry, not possible.
If you wanted to get close-to-crazy I suppose you could  create a custom String field,  copy the First Name to that field using Change Data Value,  copy the Account ID to the First Name,  dedupe on First Name,  set everything back.