My guess would be that razors where made in such large numbers, mostly by hand, that there would be different people handling the task as well as slight changes as the years when by. As costs changed etching would change and so on.

Just a guess really.

I have several robeson razors with the same part numbers stamped on them and look nothing alike. Much like yours posted above.

Obviosly counterfit, send them to me for proper disposal : D