[why the pmmh 40 bushing tuners are different from each other?]

Hi, this summer I bought a pack of Original Gibson tuner (custom shop spec, single ring kluson style) to replace the tuners to my old classic 60, when I swapped the keys I didn't had tho swap the bushing, cause they fitted already perfectly (probably are the same hardware already mounted), so I left them unused in the plastic. but yesterday I discovered a thing, the bushing are different, 3 have a single circle above in the center, the other 3 ave that circle different like in the fender ones mounted on my strat. somebody know why?  an error in the packaging? 

[greetings!]

Hi everybody!

I'm Walter,  from Italy. just an afficionado who entered in the Gibson world with a tribute 70's and then keep going further...