Seems like Marketo with its little tool, not always free, to fix the duplication problem feels that has done enough, but this problem has never been taken seriously, the marketer got use to the mess blaming himself, instead of demanding a real solution from Marketo.
I think Marketo must face the problem and help the user out there in a real way.
I understand the frustration that can happen when a program doesn't react the way you think it should. In order to better understand how deduplication works in Marketo I wrote the blog post below.
There are several ways Marketo is able to deduplicate leads when they're created, but also some ways that Marketo can't. If you have duplicate leads that have been created when they matched one of the criteria in the article and should have been deduplicated, please open a ticket with support. We take bugs and errors in the system very seriously.
What exactly is not working? I am sure John's description of the deduping will help, but there are situations that firms create where the standard Marketo deduping process will not work. If you can tell us what's wrong, perhaps some of us can point you in the right direction for a solution.
No, I don´t want third party intervention, please read the post, MARKETO needs to face the problem.
I agree that a tool like RInglead can really help you out here. Please provide further details about what exactly is going on to create the duplicates and I will see if I can come up with a solution for you