Abstract: The invention described is a method of and machine for duplex copying images present in order on both sides of two original sheets in which, in a first cycle, an image of the first original page is applied twice and then an image of the third original page is applied twice to a separate blank receiving sheets.Thereafter, in a second cycle, an image of the second original page is applied twice and then an image of the fourth original page is applied twice on the blank side of the returned receiving sheets which were already printed on one side. The two cycles are repeated for making further copies of the two original sheets printed on both sides.

Abstract: In a device for collating sheets of paper having at least one receiving surface made from electrically insulating material, a set of rolls for feeding a sheet from one side of the receiving surface and depositing it thereon and an improved charge remover for removing electrical charges from a deposited sheet comprising at least one conductor connected to earth potential which is disposed on the side of the insulated receiving surface remote from the side where the sheet enters and which forms an abutment with which the leading edge of each sheet comes into contact when it is being deposited on the insulated receiving surface, thereby removing electrical charges from the entire sheet.