Separate Systems for each Refrigerant ?

[JohnHere]

I believe that a separate recovery/recharge machine is required by regulation for each refrigerant type.

At least a couple of manufacturers are now producing EPA-approved RRR machines designed to handle both R-134a and R-1234yf simultaneously. The Konfort 780R Bi-Gas is one that recently appeared in the "ACtion" magazine, which MACS publishes. It has two separate tanks and two separate circuits for recovery, recycling, and recharging. It'll cost you, though