Can you power two L3+'s with one Bitmain APW3++ and is there any special equipment needed?
There are not enough PCI-E connectors - you need 18, APW3++ has only 10. At one point Bitmain was selling a special version of the APW3++ with 18 connectors but that's no longer available.
Even if you could get this to work with some high-quality splitters it would put the PSU at a 100% load. Probably not a good idea.