This is an 8-bit, 5.25 disk. For the 8-bit line of computers (800, XL/XE). The sticker might, just might, suggest that it has some kind of confidential data, perhaps the source of that game, Dandy. I doubt it means "trade secrets" literally. But it might be nothing, it might be just a labelled disk that was reused to record a simple copy of the game.
It would be very interesting to see a pic of that 1200 computer.
I suggest you contact some people at AtariAge, a forum more dedicated to the Atari 8-bit line than Atari Forum. User "Farb" there might help you dumping the disk, if you cannot by yourself. User "kheller2" and a couple more specializes in the early XL models and prototypes (1200,1400). They should be able to tell you everything about yours. Again, both users are at AtariAge: http://atariage.com/forums/forum/12-ata ... computers/