I've discovered an unusual situation where identified duplicate records (same email address) have been merged (merge was processed in Salesforce), but both records are still appearing in Marketo.
Prior to the merge both records would have existed in both SFDC and Marketo. Since we have a "standard" sync setting between the two systems, regardless of where the merge was processed, both records should have been merged into one across both systems.
Would be great to hear if anyone else has come across this issue before.
Do both of the leads in Marketo have an Original Source Type of salesforce.com?
That's definitely bizarre. I've come across issues where there were multiple duplicates to merge due to list imports, but not this. I would contact Support to make sure there were no sync errors (makes me wonder if there's a way to tell in the Activity History?)
If you had duplicates previously both in Marketo and Salesfore, Marketo isn't always the wisest when it comes to properly merging the two records—check to see if one is flagged as Deleted in SFDC = true.
I have noticed this issue in the past with our instance as well. There may be an easier way to fix it, but we simply merge each record manually in Marketo