1. In an automatic document handling system for recirculating a set of document sheets seriatim in a page order to and from the imaging station of a copier for making precollated copy sheet sets, said document handling system having control means and two document trays, the improvement for higher speed document recirculation for copying on a copier having a high copying rate at said high copying rate comprising: automatic document sheet separating means controlled by said control means for automatically, during the first circulation of the set of document sheets, separating the set of document sheets into two half-sets of alternate page document sheets and restacking said half-sets respectively in said two document trays; automatic alternate document sheet cooperative feeding means actuated automatically by said control means on the second and subsequent copying circulations of the document set to feed document sheets alternately from said two document sheet half-sets in said two document trays so as to feed document sheets at said high copying rate and in page seriatim order directly to be copied on said copier; and wherein said automatic document sheet separating means in said second and subsequent, but not the last, copying circulations is controlled by said control means to reseparate said document sheets after they are copied and return them to said two document trays.
4. The automatic document handling system of claim 1 in which said control means includes means for determining which of said two document trays contains odd page documents or even page documents by the end of said first document set circulation, and automatically determining and controlling from which of said two trays said feeding is initiated to provide proper precollation copying.