this just depends on if its a insump or recirculating skimmer.
if in sump, no.
if external/recirc then you can only run 1 with no problems. (just cuts the rating or efficiency of the skimmer.
hope that helps. (fins reef sells H&S in the US. you can confirm what i said with him)
also, this goes for most external skimmers. (with multiple pumps)