Two up high speed printing system

In a high speed two up electronic printing system, with a printing path direction, in which dual page images are concurrently printed side by side onto image substrate material, paired laterally transverse said printing path direction, and outputted as two parallel individual sheets, to increase printing throughput, the improvement in said two up printing system comprising:

• a feeding system for feeding image substrate material into said printing path for said paired side by side dual dual image concurrent printing;
• an electronic imaging system for line by line simultaneous two up printing of two different page images onto said image substrate material;
• said two different page images being outputted as two differently printed said parallel individual sheets;
• and a sheet output lateral sheet merging and stacking system for laterally overlapping said two parallel individual printed output sheets on top of one another in sheet pairs, and for stacking consecutive said sheet pairs on top of one another, to provide a collated output of said two up printed sheets;
• wherein said sheet output lateral sheet merging and stacking system comprises a disk stacking system which laterally shifts and superposes said printed paired sheets on top of one another while both sheets of said pair are being arcuately supported and rotated for inversion.