How do you manage Possible Duplicates?

Hi Said,

Marketo does have functions in place that manage lead duplication, it is important you have a regular data maintenance schedule ensure.

This includes:

Regularly querying for leads with matching email addresses and updating to eliminate duplicates.

Updates of lead information from the lead record with the most recent activity (except for Lead Source)

If one duplicate exists in Marketo only (ex: was created by a list import, etc), I will merge those manually if there's either no conflicting data or if there's merely a data enhancement.

If the duplicates both exist in SFDC, I will contact the owner and see if they should be merged, and then I request our admins to merge them in SFDC only.

We used to have DemandTools to help us easily manage dupes, but since we've had to drop it due to costs, the process has become a bit more manual. I have, however, learned that the above methods work for us as long as I dedicate an hour or two per month to check the list and merge any dupes I can.

http://developers.marketo.com/blog/how-to-clean-your-marketo-database/