Yes, that is possible.
Use one HP DPS 1200 for two hash boards.
Use another HP DPS 1200 for one hash board and controller.
Turn on the power supply connected to the controller last.
Do not connect the two power supplies in to same hash board, they end up "fighting" each other.
Looks like the DPS 1200 is only specd for 75A@12V on 110-120V, ie 900W
a 14TH/s S9 takes 1400W.
So if we're using one PSU for two hash boards isn't it running right at, or even slightly over spec?
No because you dont want to run a PSU at 100% load all the time, that will cause an early death. Just like with breakers, I de-rate my PSUs 20%. I wouldnt push a 900w psu 24/7 over say 700-750w max.