There were two 1954 fan blades, with 4 blades or 6 blades.

You'll see at the link above that there was an earlier, different, 4-blade fan.

It is highly likely that the different 4 blade fans you have seen were from different years, pre-54/55, 54/55, and post 54/55 (however, later 4-blade fans had a larger diameter).