Copying system

The invention provides plural precollated sets of copies by plurally recirculating a set of documents and normally making two consecutive identical copies per document per circulation, at one-half the copying rate of the copier, feeding these pairs of identical copy sheets separately into two of only three (or four) movable compiler bins, sequentially accumulating and stacking these copy sheets into completed, compiled, collated copy sheet sets in each of the two compiler bins, and the removing the sets one at a time for finishing, from the opposite side of the bins, and sequentially changing, for subsequent circulations of the sets of documents, which two of the three compiler bins is having pairs of copy sheets fed to it, and which compiler bin is not, so that a compiled set of copy sheets may be removed from its bin or left in awaiting finishing of a prior set without having any copy sheets fed into that bin, in coordination with, and without interfering with, the feeding and directing of other copy sheets into other compiler bins. Preferably two copy sheets are fed into the same compiler bin in directly immediate sequence (the second copy of one document and the first copy of the next document) to reduce the number of operations of the bin gates. When there is an odd number of documents, preferably three identical copies are made of each document in a final copying circulation of the document set and fed into all three bins, unless the copies are duplex and there are too many documents for plural duplex buffer sets.