Chances are the FFL makes an error and DROS an "off-list" model as an different (but similar) rostered model. This would not be discovered unless the DOJ did their audit during the 10 day waiting period.
After that the gun in gone (to the buyer) and the paperwork shows the sale of a rostered handgun.
"But far more numerous was the herd of such, Who think too little and who talk too much." -John Dryden