nhicap19,
It's happening because tooltip is refreshing with points even from invisible series. We have to provide only visible series points to tooltip refresh method. To find out if series is visible check if series.visible property is equal true.
Demo:
http://jsfiddle.net/wchmiel/s0unakfq/2/
Api reference:
https://api.highcharts.com/highcharts/s ... ne.visible
Kind regards.