r. shimon bar yochai explains to his talmidim that the same shaving cannot work for both metzora and for tumah

for two reasons dependning upon whether we are considering the first shaving of the metzora or the second shaving of the metzora: whether the shaving is to take off the hair or to grow the hair, or whether the shaving comes before the zerikas hadom or after. i don't understand how the answer works. obviously the two shavings are different. one is for nazir and one is for tumah. the metzora has to shave his entire body and the nazir only shaves his head (i understand that because of the sofek he will shave his entire body). so what if one shaving is forward looking and one looks back or if one is after the zerika and one is before (he can bring the korbonos in the correct order so the shaving will be after the zerika and before the zerika as required). the shaving doesn't know if it is forward looking or backward looking. this sounds like a difference without a distinction. i would even go further. in the third shaving the chatas haof may be for metzora or for nazir tamei. yet in the safek it counts for both. according to r. shimon a tenai to change between an asham and a shelamim is ok even though there is a significant difference between the two, namely the time of eating. apparently, so long as the acts are the same from an objective point of view, the intent does not matter. so what is the answer of r. shimon himself as to the use of one shaving for two purposes. thank you.

dmartin, raanana, eretz yisroel