Perhaps the "01-01-70" is a print out of a test result using some piece of equipment without a real-time clock (the Atari manufacturing department equivalent of a VCR clock blinking "12:00", for instance).
BTW, I just got a 7800 off Ebay with a board dated 2784, s/n AT8427168, has the expansion port. Just FYI if you're still tabulating serial numbers. Set me back $51 with seven 7800 games (incl. a Copyright 1984 Pole Position II white label) and four 2600 games.