Sales Representative options in Sale document header

I have noticed that, when creating a sale, not only the Company Contacts that are set up as Sales contacts, appear in the Sales Rep field e.g. a contact that is set as a Billing contact, still appears as an option in the Sales Rep field. As I understand your support articles, this should not be the case. 
Also, even though there is no default sales rep set, the new sale takes the first Sales Rep (alphabetically) as the default. This can obviously lead to unintentional errors… There should rather be nothing in the field, to force the user to select the correct Rep.