You're assuming the security paper has the form pre-printed, which isn't necessarily a good assumption. You can buy blank security paper, as for checks, for example, with nothing pre-printed, or to fit certain templates for specific programs that print checks, like QuickBooks, etc. It's easier to get now than it was a decade ago when I bought my last pack of 3-to-a-page check printing paper. Had to go with the generic paper as no one made it for MS Money AND at the same time affordably cheap. There were LOTS of options for Quicken, and others, though.
If I dug through my boxes of old stuff, I've got 2/3rds or so of that last package, and could probably print my own “birth certificate” on it. Only problem would be that I bought pre-perforated paper...
OS