smimar,
Tooltips from your demo are not showing the same values, if you mouse over the histogram series it will show values for the histogram. If you mouse over the bell curve there will be values for the bell curve series.
I am not sure if I understand you correctly, but I assume you want to have a different (or default) tooltip for histogram and a different (with e.g.
pointFormatter) tooltip for the bell curve series. You can change these tooltips in
plotOptions property (docs:
https://api.highcharts.com/highcharts/p ... ve.tooltip https://api.highcharts.com/highcharts/p ... am.tooltip).
I have also changed your demo a little bit to show different tooltips. You can check it here:
https://jsfiddle.net/BlackLabel/9cph0trw/
Let me know if that was what you were looking for.
Regards!