Do I have to wire all grounds?

[Chester]

Strange question possibly, but for modules like the RFM69's, do I have to have a fly lead to BOTH grounds? Or just one of them?

[mfalkvidd]

@Chester one is enough. They are connected to each other on the pcb.

You can verify this by putting a multimeter in continuity mode or resistance mode and measure the resistance between the two ground pads. The resistance should be zero.