Need help figuring out which bolt size for hangers

Cleaning out a shed I found a box of 30 fixe hangers.

I also already have a box of hangers/anchors and bolts from MEC, but the recent box I found in the shed have a slightly bigger hole in the hanger, meaning that the bolts I currently have are slightly too small.

My question is, can I just buy smaller washers to place between the hanger and bolt without compromising the amount of force a hanger can take before it spins?

I don't see why not, but definitely don't want to put up a route that isn't going to be safe/stay safe over time.

Well all hangers have a hole slightly bigger than the bolt, they wouldn´t go through if they didn´t. The standard clearance on a metric bolt is nearly 1mm and a bit more doesn´t change anything.
The diameter of the hole has no connection with whether the hanger spins.
You can´t fit a smaller washer, only the size for the bolt.

Thanks Jim.

I don't think I was clear enough on the issue but no worries I've got it sorted. Thanks again.