We used to do a similar thing with seed drills back in the day. A tandem hitch to pull two of them at once when we got a bigger tractor (Stieger Panther) but big air seeders had not really been invented yet. The old seed drills were a bit of a pain though as you had to manually fill the seed box with seed and super. That was originally done by hand from bags, then moved to a truck mounted bin with auger.