Possible LPG fuel contamination?

Just had the Disco V8 start missing badly between 1000 and 2000 rpm when under load and when warm, gradually getting worse as she gets hotter. No sensor faults are coming up on diagnostics. At first, suspected spark issues with LPG being more susceptible than petrol so have checked over knock sensor, plugs, etc. Then moved on to LPG filter, injectors, etc., but it's intermittent and clears above 3000 rpm so don't think it's any of the above.

BUT one of the other cars has now suddenly started struggling on LPG too. Given they've both been refuelled at the same place is it at all possible that the LPG is contaminated (say water) that's causing problems or just coincidence?

Thanks.

I'd have to go with coincidence. If it was fuel contamination I'd be suspecting the petrol rather than the gas.