I see what it is. Your "Same As" checkbox is doing that when it can't find a matching field based on the field name in the billing and shipping info.
The fields should be named the same so it can match them.
For instance you have fields named:
CompanyShipName
and
CompanyBillName
They should be named:
CompanyName
CompanyName_2
That will allow the "Same As" checkbox to work properly and get rid of the "false" values being inserted.