Deleted in Marketo, then re-created and synced down to Salesforce?

Hi everyone.

We are considering deleting a lot of people in Marketo that have been synced up from Salesforce. We use Person Accounts - when we create a new person via Marketo, the lead is synced down to Salesforce and immediately converted to a Person Account. It's then synced back to Marketo as a person account.

So if we delete someone, then we get them back into Marketo via a form fill and they are synced down to Salesforce - what would the behaviour be? Would Salesforce de-dupe a Lead against an Account? Or would it create the Account, sync it up to Marketo...giving us one Account that is synced into Marketo, and one that is in Salesforce and was pre-existing?

Trying to work out what the behaviour would be and whether it would cause any downstream problems. Thanks!