This is normal and how it should be. The RHS collar should have no spacing effect; if it does, you'll have alignment issues. There is no fixed spacing on the RHS, the fork position (and caliper) is completely determined by where the axle is in relation to the fork leg when the pinch bolts are nipped up.

As it is only your RH disc and caliper that are making contact (I'm assuming the LH is fine?) it can only be the fork alignment causing the issue. If it was on the left (or both sides) then the spacer could be blamed - there is only ONE spacer on the front axle and that is on the left and is held in place/position by the axle's tightening torque. Both the disc's positions are fixed in relation to the LH fork leg. The spacer however has no effect on the relationship of RH disc and caliper position; that is governed by the axle clamping position only.

I would guess that the garage that did the work didn't align the forks carefully enough by tightening the axle, compressing and releasing the forks several times and then tightening the pinch bolts. Even if they did follow the correct procedure, alignment can still get fouled up if the mudguard was not removed which, if left in place, causes the forks to splay out (and the inner side of the LH disc will contact the caliper).

As mentioned, lettering on the RHS. Also look closely at the hub - the LHS has a longer 'nose' casting (bearing carrier) protruding out from the webbing than on the RHS.

An exploded diagram might help too:

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