As far as I know, the OEM F08's the dual shock R65 comes with uses a 36mm piston; whereas the F08 the Ducati's use have a larger 38mm piston.
Although the some of the 38mm piston versions will fit the R65, I dunno what will happen if you use a 36mm piston on one side and a larger 38mm piston on the other with respect to dual disc systems.
The only bike I know of that also uses this 36mm F08 is the R100 for it's rear disc.