The associative desorption of HD (v,j) and D-2 (v,j) on a graphite(0001) surface via an Eley-Rideal mechanism has been studied theoretically using a time-dependent wave packet method, We find that product molecules are formed rovibrationally excited and translationally hot. When comparing the different products to earlier calculations on the formation of H-2 on graphite(0001), we find significant isotope effects and possible resonant transitions during the reaction, which might have consequences for the possible detection of highly excited H-2 in dense intermolecular clouds.