I couldn't find this issue anywhere in wiki so I have added it here. We came across another example of this in ITAS this week for Marketplace Orders. Here are specifics:
Email from c/e to ITAS:
I quoted the customer (Xpedx) in Market Place. The bill to address needs to be 080126 but, because the contact is in the system under a different bill to address, Market Place changed the bill to info to the contact’s default information. I cannot convert the quote since the info is not syncing up. Sarah has run into this issue in the past with a Unisource order, and she believes she created a fake person to create the quote, but she wasn’t sure if this was the best solution. Please advise. I currently have the order on hold.