The description of the problem appears to be related to a worn out drum or imaging unit. Laser printers use a drum unit to transfer toner to paper. If the drum is faulty, it can cause residual toner to remain, which can then create 'echo' images on subsequent printouts. Replacing this component is often the solution for resolving double or echo images on prints. Replacing the toner cartridge may not necessarily fix the issue, nor would the transfer belt, which is responsible for holding the paper steady and applying pressure during toner application. Cleaning the print heads is relevant for inkjet, not laser printers, and would not cause double imaging.