sayasan - Great answer!
Bern received razor canceler 4.01 on 10 October 1898. This is identified by counting the number of hachures [13 top, 14 below]. The device was the only Bern razor device available on 2 July 1900 (top), the first day of issue of the UPU series of stamps and postal cards.
The next Bern razor canceler, 4.02, was distributed for use on 10 September 1900 [with 8 hachures top and 8 bottom] (bottom). This item, canceled with the Bern 4.02 device, therefore, is not a legitimate FDC item. One can only assume a collector had a postal employee friend backdate this for his collection. The fact the clerk used the 4.02 razor device set to 2 July proves neither the clerk nor the collector had any idea this item was being canceled with a device that had not yet been manufactured! If the clerk had used any other of many cancelers available to Bern post office employees, we would have greater difficulty questioning its authenticity [see below]. This collector/employee collaboration was done before December 1901 when the 4.02 canceller was removed from service.
Another interesting fact is the first series of UPU stamps were line perforated, while a new printing of stamps issued after 12 July and September 9 were comb perforated. All the stamps on the false cover are stamps issued after 12 July, therefore, couldn't possible be first day uses.
