Not a spare run 2 
One on the outlet, and one on the return? Reckon there is much advantage?
Yes for redundancy if not for performance
Although I have now ordered a new pump, I manage to fix the the chargecooler pump yesterday. Turned out to be a corroded in line fuse - bit of wd40, a new fuse and all seems well again. Nice to have some of them lost horses back!!
Still not got to the bottom of the leak though. Took the chargecooler off and couldn’t see anything obvious so will continue to monitor levels - if it drops again I will just have to send it to Proalloy to be pressure tested.
I would take it to your local garage and get them to stick a pressure tester on the whole system and see if you can find the leak, take off the induction pipes going to it then you can see if there is any water coming out.