This is what i was wondering....Yes the zappi con work without internet, it does use it for updates to software though.
If you only have a 60a supply then I would use a harvi to control the two points so they don't end up using all the supply capacity. Although you can set a maximum current limit in the charger to stop them taking the cut out fuse out if both get used together!
CT clamps will keep them from pulling too much, but with a dual unit... (2 cars plugged in at once into the same unit) Can one be set as priority, and the second one kick in when the first is at 90% or whatever.... or say, charge car 1 for 6 hours, then car 2 for 2 hours. ???
Might not be so easy with 2 x individual units