Thanks for the details.

So it happens with autoclose and newer. I'll search this way.

When you write "all duplicate tabs are closed" you means only the existing one and the new one?
Did you noticed if the older tab was completely loaded? or if both tabs were loading?

I guess you haven't be able to reproduce the problem with the same URL?

****Update ******
I've found something that can explain your problem.
I'll push a fix soon.