Gass Cover Find-With Question

Just got back from 5 days at GASS in Cleveland. Besides exhibiting (a 1st day cover exhibit of the 1988 65 cent Hap Arnold definitive, and a literature entry of my three part series in FIRST DAYS on the WWII patriotic covers of Victory, VT) I spent hours going through dealer boxes, mostly looking for Victory, VT, covers. Of the 20 or so that I came home with, the following was the most interesting:

What is notable about this cover is that of the several hundred Victory, VT, covers in my possession, and of all that I have ever seen, this is only the second with a postal marking that indicates it entered the mail stream. Undoubtedly many, many, more did enter the mail stream, but without postal markings beyond the postmark itself there is always room for doubt whether addressed covers actually entered the mail stream, or were handed back after being postmarked. Both of the two covers now in my possession with evidence of entering the mail stream received markings from being forwarded after being received at the post office to which the covers were originally addressed.

My question: the postmark applied by the receiving office (Augusta apparently handled mail to and from Camp Gordon during WWII) to the back of the cover wraps around to the front of the cover. I've seen examples of backstamps bleeding through to the front, but a wrap around? I am not familiar enough with how machine cancels work to understand this. Can anyone explain it for me?

TIA.

Basil

I suspect that it is just offset (I also think that I might have been standing there when you bought this cover, although I am not 100% positive).

The Augusta machine was not adjusted quite correctly, such that the killer bars ran off the end of the letter and the last bit of the wavy bars printed on the various rubber feeding rollers. Then transferred back to the reverse side (in this case, the front) of the next letter passing though the machine.

"...just offset."

Still not sure I understand. Does the canceller employ a rotating drum of some kind, so that if the cover is not positioned properly some of the postmark ends up on one side, and the rest on the other?

Edit: John posted an explanation while I was uploading this one. Thanks, John.