I have gotten this weird error the past day or so, not quite sure what to make out of it, and well, I can not report it directly on the BugGrabber addon.

129x Deferred XML Node object named L_UIDropDownListTemplate already exists
!BugGrabber\BugGrabber.lua:578: in function <!BugGrabber\BugGrabber.lua:578>

Locals:
nil

129x Deferred XML Node object named L_UIDropDownMenuTemplate already exists
!BugGrabber\BugGrabber.lua:578: in function <!BugGrabber\BugGrabber.lua:578>

Locals:
nil

172x Deferred XML Node object named L_UIDropDownMenuButtonTemplate already exists
!BugGrabber\BugGrabber.lua:578: in function <!BugGrabber\BugGrabber.lua:578>

Locals:
nil

Addon error, nothing to do with BugSack (or buggrabber).
Looks like one of your addons is using a library for dropdowns, and that library is causing this issue.

I switched off the addons until I got the one that stopped the problem and could repeat it by enabling it again. Hope it is the only one. Broker Keystone. Reporting on their addon instead.

Thank you

Thanks for the work in tracking this. I checked, it uses a library called LibUIDropDownMenu.
It seems someone has already reported this issue to their author:
https://www.wowace.com/projects/libuidropdownmenu/issues/1
I would recommend giving it a bump and expanding on the fact that this issue now appears in game and affects any addon using that library.

There are quite a few addons using it:
https://www.wowace.com/projects/libuidropdownmenu/relations/dependents