CircuitMaker: Nets Wire JACK_IN_GND has multiple names, why is this bad?
Having multiple nets with different names would seem to indicate an accidental short in your schematic design entry. It could also be confusing if you are reading a schematic. Some PCB software won't allow it at all, requiring all connected signals to be named the same thing.

If the pins are intended to both be connected to ground, simply connect both directly to ground rather than giving them intermediate names.

If your purpose for wanting to use the net name to help you work out which pin is which on a header, you are better off using text labels for that. Name the net based on what it is connecting to (GND), and add text next to the header to provide extra info on where the pins are to go off-board.