Hello my friend 😉
In your place I will leave the 2 at full power because the led is not greedy in electricity your 2 lamps consume just 0lus a 250 watts hps.
I use myself 2 leds 300w lamps that I leave in 20/4 because I only grow autoflowering. And my bill has not increased very much. I advise you to put them at the height recommended by the manufacturer following the growth phases of your plant (me 90 centimeters growing and 60 in bloom)
That's what I do and I'm very happy with the performance.
I invite you to see my different test to get an idea.😊
growdiaries.com/diaries/37722-differents-tests
May the strength be with you 💪