4 to determine whether each of the data segments in the data buffer 2 has been copied into all the random access devices 5 and if one data segment in the data buffer 2 has been copied into all the random access devices 5 read a new data segment from the source data into the data buffer 2 to replace the data segment that has been copied to all the random access devices 5 and a second determining step s 5 to determine whether any of the random access devices 5 has saved all data segments of the source data if one random access device 5 has saved all the data segments of the source data finish the data copying of that random access device 5 and inform the operator of the one to many reproduction apparatus 1 to remove the finished random access device 5 repeat the steps set forth above to continue the data copying process the invention further may include a comparing step to read the data segment already copied into each of the random access devices 5 and compare the read data segment with the original data segment of the source data to check consistency to confirm that the data segments copied into each of the random access devices 5 are correct please note that this comparing step is not illustrated in the figures please refer to fig3 for the structure of a first embodiment of the invention the random access devices 5 are two usb disks 5 a.