15 Amp, 125 volt branch circuit with duplex 15 Amp, 125 volt receptacles. Plugged into a single duplex are two 6.5 Amp (nameplate) commercial referigerators, one into each position. For the sake of discussion there are no other loads. Does this violate ANY ratings or NEC requirements?

I would say no.
I believe a refrigerator is not a continuous load ( on for 3 or more hours). The compressor will cycle on and off but should not run continuous.

210.21(B)(2)
If the "duplex" receptacle is considered 2 receptacles, (and I believe it is) you would have a violation.

Redsy, since this is in fact two receptacles, neither one would be loaded to the maximum limit of Table 210.21(B)(2) for a 15 amp receptacle.

Roger

OK, so it's per each receptacle?

No overload, no violation but poor design. Just a matter of time before both units start at the same time and that could spell problem.

And no argument...

To change the question slightly...
Suppose the duplex were split and each receptacle had it's own 15 Amp circuit.
A load of 12 Amps could be connected to each, giving a total current of 24 amps through a standard, everyday, less than $1, duplex receptacle, correct?

Yes that is correct.

Now how long would that cheap receptacle would last is another question altogether.