Looks to me like the body of the letter was printed onto paper pre-printed with the letterhead, but that the paper was fed through the printer at an angle. My

Looks to me like the body of the letter was printed onto paper pre-printed with the letterhead, but that the paper was fed through the printer at an angle. My guess is someone then said "eh, good enough, I can't be bothered going to get more letterhead paper out of the box to feed into the bypass tray, then going to re-print the document from my computer", and took the letter to Senator Wyden for signature. He then signed, and the signed letter was scanned for preservation as a digital record.