2 Square meters is a 21 sq/ft area. A 600w HPS is good for a 3ft x 3ft area. 9 square feet. Or 36 inches x 36 inches. A Meter is 39.37 inches. So 2 of the 600w will be good for a 6 x 3 area, or 18 sq/ft. Or 1.67 sq/m. A 400w is good for a 30 inches x 30 inches 6.4 sq/ft or .58 of a meter. And it will have to be much closer to the canopy vs the 600w.
Really the 600w, and 400w foot print, and height from the canopy, arent compatible. Id just use the 1.67 sq/m size, and 2x 600w HID.