Marketo not removing duplicate email addresses in batch campaigns

[Anonymous]

Hi there - I'm testing a campaign which is using 3 lists generated from our existing SFDC database, There are duplicates within each list, and also across the 3 lists. I read through the "managing duplicates" section from the community guide, and I assumed that Marketo would automatically filter out duplicates with the same email address, but it doesn't. Here's what the guide says:

"In another case, say you run a campaign to email your lead database and two duplicates are included in your campaign run. Marketo automatically detects the duplicate email address and ensures that only one email is sent to that lead. That email send and subsequent activity will be attributed to the most recently updated lead."

Here’s what I did that ended up having the same email sent to 2 leads with the same email address:

I batch ran the campaign once when there was only one lead with the same email address – then I manually added a second new lead with the same email address and batch ran the campaign again, and the newly created lead with the same address received the email.

Is this because I ran 2 separate batches?
 

Is there campaign logic I can setup in my smart list or flow that will prevent this from happening when I run my live email send?

[Anonymous]

After running multiple tests, it appears the only way to prevent multiple sends to the same email address is to combine the 3 lists into 1 so that Marketo's automatic de-dupe by email can be applied.

It would be great for Marketo to extend this feature so that separate batch runs within a program can also be prevented from blasting an email address from receiving the same email more than once.