actually I just figured out that it wouldn't work, as the dumpOSC object can't listen on the port that's being used by sendOSC.
OSCx is half duplex. if you are unsatisfied with using seperate ports to send and recieve , you could look into enabling liblo in pd via Flext, or some of the OSC reflectors/managers like OSCgroups and a couple others whose name i can't recall..