Some pairs of shoes come with different thickness of lining - one thick, one thin. This is a modern development which is hard to fathom. You might not know for sure until you get a new pair.
If it's a single cylinder set up then the shoe which faces direction of travel at the hydraulic cylinder, will take most wear.
If the shoes are identical then I would try swopping over. Note if there's an auto adjustment - sometimes not obvious, and punp the pedal well and operate the handbrake to take up the slack before you drive off.
