Aerogramme With Watermark? Nope

My daughter and I were transferring our recent non-online auction acquisitions to another album and saw this bleeding through. It kind looked like a watermark I was very curious as to what it was. We had another that did not show this and it made me open to reveal the apparent stationary/ letter head of INTER-OCEAN TRADING CO in California.
Just figured we would share it.



Sadly it's folded and has staple holes, but we still like it.

Inter-Ocean must have used a lot of these to think about getting a letterhead printed. Printed letterheads aren't seen very often. With the flimsy paper, there must have been a fair number of spoils.

Thanks hy-brasil for the reply, We thought it to be odd, so we shared it. Yes, any mistakes could add up quickly. I'm glad I wasn't the one doing it.