Is it possible to run 2 Ender 3's off one power supply?
The heated bed alone draws 220 W of 24 V power, so I'm going to say no, you shouldn't attempt to run two Ender 3 machines from a single power supply.
Instead, because the whole machine only draws about 3.5 A at 115 V (or half that at 230 V), you should consider installing a power strip or (better) a small UPS to both power both machines from your existing outlet(s) and also protect the machines from power surges and short power interruptions.  You won't overload your outlets, and you won't risk burning out a power supply by drawing twice the power it's built to provide.