I'm no expert on the printing process, but my speculation would be that these were test cards to check alignment, like what you do at home when you replace your ink cartridge. Having a black, rather than yellow, border and a symbol that is slightly off center in both examples makes me think they wanted something simple to reference to make sure things were adjusted to be centered before running mass amounts of cards.
If these are 15 or so years old wouldn't Wizards of the Coast still have been the company printing these? If so maybe do some searching to see if there are similar cards out there with Magic the Gathering backs. I would think the process would have been the same for both games, and Magic was around much earlier so might be some of those out there.