I am redoing my kitchen. All of the duplex outlets are on two 20 amp
12 awg wire breakers. However...all of the old outlets are rated for
15 amp circuits ? I have come across this in kitchens many times
before.

Can you use duplexes rated for 15 amps in the kitchen with 20 amp
breakers...fed by 12 awg wires ? Is this a common practice and OK via
NEC...or should you use the 20 amp duplexes with the horizontal little
plug fitting on the receptacles ?

Thanks, TR