I have seen photos of the setup and actually, both pumps are belt driven. He has built a setup that installs a shaft in the position of the original IP. This shaft sits in a frame setup and drives a cog belt with an IP hanging on either side. Tee-ing multiple injection pumps together at the delivery valve (a sort of check valve) is nothing new. This has been done multiple times with a 12 cylinder "P" pump on a 6 cylinder tractor.
While this guy's 6.2 tractor does run good, he still is only getting about 180cc's of fuel max. So he probably isn't turning that HX50 charger as hard as one would think. For a real show, let him install an 8 cylinder P pump!!!
If you google "6.2 tractor lambert ter heide" you will find the article on "The Page"...
Regards,