You can still use two 1000w PSU's to run them so you are still kind of wrong

dual
psus is dangerous had them catch fire before , crossing rails by accident I NEVER use dual psus anymore
I see no issue to power cards from multiple 600 or 700W cheap power supplies.
I am powering 6xR9 390 with six PS that in total, cost me app. 200$ and it works fine for months
Important to mention that 390 in dual mining draws close to 300W each, 1800W total.
You cannot get 2x1000W PSU for 200$