Question on OEM websites

[Lamb]

i'm looking for a replacement air screw with spring, since the other spring mysteriously disappeared. i haven't gotten any responses in the classifieds, so i've turned to the OEM sites, like this one

my question is- why, for the air screw (and many other parts), are two different prices/models listed for the same #6 (i noticed this on other OEM sites as well)? can i expect both #6's to work?

thanks