Lead scoring and duplicate records

We are implementing lead scoring with Eloqua, however, our Salesforce instance has some duplicate records.

We are trying to understand technically what happens when Eloqua is sending updates (exports) to Salesforce when duplicates exist in Salesforce.

For example, let’s say Contact 1 in Eloqua has two duplicate corresponding contacts (Contact A and Contact B) in Salesforce. In Eloqua, Contact 1 performs an action that increases their Lead Score. The next time Eloqua scheduled to sync to Salesforce, does it update Contact A or Contact B, or both? Or neither? And why? 

Thanks!