We frequently have contacts who either own two or more different companies, or work for more than one of our customer companies. There is currently no way to associate one contact with more than one company - which means we have to duplicate the contact. Such a contact will typically have different email addresses for each company - but the same mobile number.
Same with us. We have many freelancers working for many different companies but use the same email addresses. We have to create them as a contact once on the system and then create a 'placeholder' under the company and put the order on there, then relate the order back to the contact.