I would expect if you are using Auto-open in combination with some buttons in the ribbon that after document opens with taskapne on the side you'll not end up with two Taskpanes after you click some navigation button in the ribbon.
I was playing with Auto-open Taskpane online example at https://github.com/OfficeDev/Office-Add-in-Commands-Samples/tree/master/AutoOpenTaskpane
and if you set auto-open on and save document next time you open document taskpane opens which looks like normal behaviour.
Strange and unexpected behaviour is when you open the document and click ribbon button "Auto open sample" it will open additional Taskpane and you'll end up having two Taskpanes.
https://github.com/OfficeDev/Office-Add-in-Commands-Samples/tree/master/AutoOpenTaskpane
Any update on this one?
Weird - I'll look into it, sorry for the delay @dgrudenic
This is definitely a bug and a fix is being looked into
@danielgwilson Any update on this? Or can you tag the current feature owner?
Thanks.