Military Censor WWI Postal Card Killer

Hi,
My question involves the killer on the stamp area of this censored postal card. It is not part of the Washington D.C. Cancel. It almost looks like a precancel of some sort. Does anyone know if postal cards were printed or pre-stamped with a killer for military use?
Thank you.

Your card suffered a misfeed into the canceling machine - taking two slightly overlapping cards through at once - the top card getting the majority of the first cancel impression and the bottom card (yours) getting the remainder. Most canceling machine ware adjusted to feed letter-thickness mail, so it easily pulled through 2 postal cards at once. When discovered during later sorting operations, is was run through again obtaining the complete cancel. Nothing special. It is not a precancel.

The censor marking is actually far more interesting. Why would an internally used postal card be censored in the first place? Unless it was sent from a sensitive location within Washington?

Thank you John,
Duh!!! What a simple thing and I didn't think of it! The placement seemed so straight and ideal for precanceling that I jumped to a weird conclusion.

Yes the Censor is more interesting. I've never had this particular marking before but that doesn't mean it's scarce. The back of the card reads "I've arrived safely overseas Frank". This was the end of WWI I think this card was sent back to the US, perhaps in a batch, and then processed in Washington. I've seen that before. I don't know if the idea was to disguise the source? Country? APO? or just logistics. Maybe someone will chime in.

Oops! Forgot to mention... The Washington Postmark was another reason I thought the killer might be a precancel of some sort. I thought maybe they distributed precanceled cards to the soldiers that were then sent back in a batch. .... Don't ask where I get these ideas, I'm old and maybe senile

World war 1 didn't finish till November 11th 1918. US troops were still arriving in Europe in June though they had begun to arrive in 1917.

The US troops began arriving in June, 1917 and did not leave until August, 1919 though there was still a small occupation presence after then. The total number of US troops was around 1.2 million and they were all churning out mail back to the US and folks from home were sending them large quantities of mail as well. The war ended on November 11, 1818, but there was a need after the war ended for large numbers of occupying forces while the treaties were being negotiated and signed. In my opinion, mail sent after November 11, 1918 is not really Great War mail (They did not know at the time that there would be a second world war so at the time it was just called the Great War, and afterwards some people also called it the 1914-1918 war. Everything was being censored so this postcard that was sent back to the US in a large batch and being censored in Washington is interesting but not unique or necessarily rare. I also note that the sender did not include his unit, nor his return address, nor any indication of where he was which reinforces the thought that this was likely one of a large batch that was sent back to Washington for processing and forwarding to his folks. Collecting Great War censored mail is fun and most of it is not very costly so a nice collection can be built without going broke. The collecting area is so large that it helps to focus on one area. For example, one can collect censored mail that is from marines, or from nurses, or from tank units, etc. etc.