Synch one field to both Leads and Contact fields in Microsoft Dynamics CRM

I have one yes/no field in Microsoft Dynamics CRM Leads entitity which carries over to Contacts when they are qualified. The Leads field is synched with Marketo, but I wouldn't want to have a separate field for Contacts in Marketo. How can I synch the same Marketo field to both Leads and Contacts, as it will be the same value? 

THanks