weird this var bug

[AvPPoW]

hello, while working on jobs for dd I have recently encountered bugs that involve this.vars, refresh my memory, this var's keep track of vars for the local npc right? Well anyways let me give you an example. In my mining script I use this vars to keep track of a rock/gem's life. If one player starts to mine and another player hits it while he is mining it reverts to starting progress. Like if the ore was on stage 3 (6 different stages) and he hit it the ore would revert back to stage 1, and then if I hit it again it would be at stage three again and so on. how can I resolve this?