yeah there shouldn't be any type of shims in there, they may have been placed there by an uninformed PO.
if there are no markings on the cap just look at the cap and you will see one side is higher than the other, this is the front side.
Always tighten the front side first, then the back, this will leave a gap in the back.
it is my understanding that if it is not done this way, the studs on the fork legs can break off.