Some applications which I have pinned to the taskbar get split into multiple icons; ones which are pinned and those which are not.
Here is an example:
On the far left is mintty which launches mintty.exe. If I create terminal windows from that icon then they stack. If I create instances of mintty elsewhere, such as from an explorer context menu, then it stacks on a new icon.
Next is Eclipse, which launches eclipse.exe. It spawns a new icon and never stacks.
Lastly is Minecraft. The first icon is the lancher which does stack. But then when the game launches it creates a new icon.
How can I get these applications to always stack without getting split into new icons?