When I open an application button pinned to my taskbar, normally the app just opens, and an underline appears under its button. Yet when I open certain applications, they open under a duplicate button on the taskbar.
This is an example:
As you can see, I have Chrome, Slack, Explorer, and Foxxit Reader open, highlighted in green, all with just single, underlined buttons, but with Visual Studio, highlighted in red, the pinned button is not active and there is a duplicate button a little to the right.
Why do some apps do this and others not?