We have a serious duplicate issue in our marketo & salesforce instance, and here are a few things I think are causing the issue but I need help figuring it out:
Thank you in advance for helping!
1. Ok generally, a 1:1 sync is ideal. So everything in MKTO is in SFDC and vice versa. But if you think about it sometimes you don't need certain SFDC lead/contact records in MKTO (partner records for example may not be someone you market to) and same with records into SFDC (sometimes if leads aren't qualified enough or don't have certain fields filled out, they may need to stay in MKTO depending on your whole setup and lifecycle). But in your case it sounds like you've deemed the record to be junk and not even worthy to label "recycled" or "trash" - you want them gone. In this case, I'd also remove them from Marketo to eliminate such issues as you're running into. However, I'd first suggest that you formalize which records you are deleting, and why. And have a process to export their data first so you have that history stored somewhere.
2. Best practice is to upload lists into Marketo. Marketo dedupes automatically by email address (unless you have Support setup a additional criteria on the back-end). This also allows you to directly attribute these names to certain sources and programs.
3. This really depends on how you have your systems integrated. Do you have any custom sync filters setup? Are there certain leads being kept out of MKTO? There are a lot of factors here that could affect this answer so I'd encourage you to test it!
Thank you for responding! Super helpful! I have another great example - which I think is giving me more reason to advise against keeping deleted records in Marketo - there was an email we sent out the other day - and for some reason, Marketo decided to include the "deleted" (deleted from Salesforce) records in the email send & add them to the salesforce campaign - even though that same email address is associated with another record (that is NOT deleted in salesforce). I wonder why / how Marketo favors one record over another? Shouldn't any record with that associated email be added to the campaign? (salesforce and/or marketo)
The above goes back to one of the issues causing duplicates in salesforce - records that have been deleted get picked back up & pushed back into the system, even though another record has the same exact email & has not been deleted from salesforce.