Apollo 13 & 14 PRS Postmark Variations

Recently Luc Jallot found what appears to be an interesting variation in Apollo 13 USS Iwo Jima postmarks. I've since found a similar variation with my Apollo 13 PRS covers.

(Click image for a larger version of the postmarks)

I've also found a similar variation with Apollo 14 USS New Orleans postmarks.

(Click image for a larger version of the postmarks)

While an initial view tends to indicate ink density variations, I believe a closer look shows distinct font variations. In particular, compare the AM in each postmark and particular the spacing between the A and the M. Does this show that two different postmarkers were used?

I would appreciate any feedback on these covers. Direct comments to the Webmaster.