For example, your part has two GND pads with the same pin number, then when you will add footprint to objects, the footprint will have only one GND pad, no two GND pads.
This is a bug. Sure you can add some other pin number to pad and then you will have 2 GND pads but with other pin numbers. It will be good solution when you have a few pads with
one number, but for example when you have 40 pads with one pin number, changing pin numbers manually will take a lot of time.
Part example: