At present, cryoSPARC doesn’t allow a dataset to include images collected at multiple voltages (most probably from multiple microscopes). Combining data from different microscopes requires some care (in particular, making sure both microscopes have magnification properly calibrated) but there is no reason that I can think of why combining voltages should be disallowed. I can see multiple voltages being useful: in our lab we screen samples and calculate maps with our 200 kV microscope and then (for well-behaved samples) collect more data at 300 kV. The 300 kV data will provide the best high-resolution information but the 200 kV data can still improve the SNR at low resolution.