it means that they were built in 86 but reconditioned (cleqaned up, fixed and sold) in 2000. honestly "reconditioned" is just a vague term now, and that means that the car has been repaired...
just treat it as a 86 as that is what it is. people just try and fool you into thinking it is newer by saying "2000 quota" or "registered in 2000" etc.