EDIT: No great rush for me. There's a standoff/screw already installed on the actual slot. So, maybe the packages are for smaller M.2s. If anyone knows the answer, though, it might help other people later.
OP: I'm preparing to install my new ROG Strix X570=I Gaming motherboard. It's got two M.2 slots (the M.2_1 one on a riser on the front of the board and the M.2_2 one on the back of the board). The box contains two DIFFERENT sets of Standoff/Screw packages for the M.2 slots: 13020-01811700 and 13020-01811600. The "600" version looks bigger than the "700" version. But, AFAIKS, there's NO DOCUMENTATION saying which one to use in which slot. Looking around the web, I found one other post for another Asus motherboard saying that, as far as he could tell, the bigger "600" version is for the M.2_1 slot. Can anyone confirm? Does anyone have a pointer to some kind of official documentation?
And for Asus: Instead of putting silly part numbers on the bags, how about just stating what the part actually is? Failing that, how about noting the part number in the manual?