'56,
Have a look at the following:
210.21(B) Receptacles.
(1) Single Receptacle on an Individual Branch Circuit. A single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch circuit.
The NEC Handbook Exibit 100.6 states the following:
...A branch circuit that supplies one duplex receptacle that can accommodate two cord-and-plug-connected appliances or similar equipment is not an individual branch circuit.
Table 210.24 is very helpful as well. The "laundry circuit" in 210.11C, and 210.52F, IMHO is not a "washing machine circuit". In other words, if there was another laundry related piece of equipment in the laundry room, it should be allowed on the circuit. An example would be a dedicated receptacle for a "built-in" ironing board. The wording in 210.11C is
laundry receptacle outlet(s), not
washing machine outlet.
Now, I said all of that to say this. If I were installing the electric in a laundry room, I would install a single (simplex) outlet at the washer. I would also add other outlets, in the laundry room only, to the laundry circuit. Heck, as far as I know, there may be some appliance that can help me with 1. the grape juice on my oldest daughter's shirts, 2. the yellow 77 stains on my Wranglers, and 3. the "bacon strips" in the Watt Mama's underwear......
Taking out the laundry,
Doc