passmore asked me the question a couple days ago so i had a little look into it also.
matt at scotts was kind enough to explain to me the two way and one way damping. but then told me he personally doesn't ride so he may not be the best doode to speak to about it.
well... i was down at the dealer anyways getting some oil and stuff so i asked my bud benny if he could help me out. now benny looks quite young, but he's been around superbikes almost as long as creeper. and he knows his shit. he was kind enough to give me a street type damper he had in stock to compare to my dirt one.
like scotts said they do look identical. yes mine damps moving away from center, as does the street unit. here's where i call bullshit on scotts... the street damper and the offroad units don't appear to have much difference on the return to center. i find the difference to be ever so slight and could maybe be me. i didn't have the plan at the time to switch them up and try (incase i gave him the wrong unit back) but maybe i will.
for now it's like the clorox commercial... i can't see the difference. can you see the difference?