I’m getting the same bug mentioned in this thread:
I don’t know if this helps, but it appears to only happen to me when the other player is also a site supporter.
@anoek are we running one for each site supporter, and notifying both? 
when multiple windows with ogs opened, sometimes i have to close it in each window, and other times there is no notification
Yeah, today my airline popped up a dialog saying “we noticed you are using multiple tabs: please don’t do that” (words to that effect) 
It’s a pain, that’s for sure.