Created attachment 46 [details]
This patch should add the StartupWMClass to the .desktop file
The elementaryOS dock is unable to correctly associate the dock icon of a running application with its main window, leading to a duplicate dock icon right after starting such an application .
The fix is to include StartupWMClass=Asunder in the application's .desktop entry.
I've contributed this as a patch to the flathub repo  of Asunder, but it would be preferrable if this fix could be included upstream. I don't believe adding the StartWMClass explicitly has any negative side-effects.
I've attached a git patch that adds this line to de .desktop file.