Do exterior duplex electrical receptacles have to be on multiwire branch circuits?
A dual circuit (where you have one hot conductor on one outlet and another hot conductor on a second outlet and they share a neutral) may not be 'required' anywhere.  This kind of circuit is called a 'multi wire branch circuit', if you're having trouble finding the right verbage to find out it's required in your locality.

It probably should be a GFCI outlet at any rate.  It may or may not be code where you are, but it's just a good idea.