If you have the bar linked to the hp on the sheet, it is altering the sheet value, which will then alter the bars on every other token linked to that sheet value. When linking npc tokens that will have multiple instances on the map, you need to link the bar to the stat and then unlink it again. The numbers will stay. Then you save that to the sheet as the default token. Then when you drag out each one, it will have the original full hp, and won't affect the sheet or other tokens when edited, because they aren't linked together anymore. Basically, you only want to leave bars directly linked to stats on PCs and possibly on unique npcs.
