in a document copying apparatus of the type having a &# 34 ; spot &# 34 ; color capability , an automatic document feeder and a multibin sorter , the copier &# 39 ; s logic and control unit is programmed to automatically switch from a &# 34 ; recirculation &# 34 ; mode , to which it defaults unless instructed otherwise , to a &# 34 ; sorter &# 34 ; mode in response to a signal indicating that at least one page of a multipage document being copied requires that a copy sheet be presented twice to an image transfer station to complete the copying thereof . as a result of this automatic change in operating modes , fewer &# 34 ; skip &# 34 ; frames need be introduced during the copying operation , thereby enabling the copier to produce multiple collated copies of the multipage document more efficiently .