What Artisi says is true for identical parallel pumps, but you have said your pumps are different. Also be careful about calculating heads, as it should be differential heads.
It may also be that the suction of the two different types of pumps vary. Are the pumps feed from the same suction line? If not any difference in suction pressure must be included. BTW, as Artisi said, your discharge pressures should be roughly the same, except for any discharge header flow losses between pump inlet points. I note you have both 150 and 170 psi.
The pumps use energy to produce a differential head between the suction and discharge. You have only told us what I believe to be the discharge pressure, not the differential head. Differential head must be calculated from the difference between discharge pressure and suction pressure. If suction pressures are different, you have to do the efficiency calculations for each pump independently.
To calculate the efficiency of different parallel pumps, or identical parallel pumps with different differential head outputs, I would use a weighted average of the sum of the individual efficiencies.
For a pump, the efficiency equation is,
A pump's differential head (in feet) is calculated from suction and discharge pressures as,
dH_ft = (disch_press_psig - suction_press_psig) * 144 / 62.4 / SG
where,
SG is the fluid's specific gravity (=1.0 for water).
Hydraulic power (power to be delivered to the fluid) for each pump is,
Power_Hyd = Q_gpm * dH_ft * SG * 62.4 / 60 / 7.4805
where,
Q_gpm is the pump's flowrate in usgpm.
Efficiency is Power_Hyd / Input_Power
I would then multiply each pump's efficiency by its flowrate, then sum that for all pumps and divide by total flowrate.
I put a small Excel spreadsheet here for you that does the above calcs at,
