Seems to me that all 4 outlets may be fed from the same 50 amp branch circuit / breaker [all 4 outlets on the same branch circuit].
Reason[s] being that at this time, there is only one load device intended to be used at one time, and the outlets are for Convenience only - rather than intended for multiple loads to be connected, or run together.
Even if two loads were connected at the same time, this should not be a non-compliance issue to the NEC, because if the circuit is overloaded the OCPD should trip.
This would fall more under the "Bad Designing Conscept" for which at this time there is no Federally Backed Code
Last I saw in Article 90, the NEC couldn't care less if things run inefficiently, per designed criteria, or without some level of inconvienience
[per non-life threatening or non- hazardous results things
It [NEC] just doesn't want any Hazardous Situations installed by the installing Gods <hee, hee, hee>
Am I correct, or should I put on the Straight Jacket???