My CVS wouldn't let me use it twice on the same transaction - I had to get two sets at once both for the same child. At the time, I thought they were just blowing smoke, but since my copay kicked in on the second set, I didn't push the issue. CVS charged me my deductible for the first set ($200) then gave me the $100 off and my second set was just the copay, so total I paid was $135 for both sets, but my insurance thinks I've met the deductible. They should have let me use the coupon on set 2 for $35, but it just wasn't worth arguing.