No, you don’t get two of the WD500, you get one WD500 and one WT00Z.
Put the WD 500 in the master position. This is the one that can control the current to the light fixture.
Put the WT00Z in the auxiliary position. It will essentially function as a wireless remote for the WD 500. The WT00Z is not a battery powered device. It will be wired into the wall, but it doesn’t have to be on the same circuit as the WD 500.
https://www.nortekcontrol.com/pdf/manuals/WT00Z1_manual.pdf
By setting these up for direct association, you will get the fastest possible interaction between them. But the master switch, the WD 500, doesn’t support association, so if you have 2 WD 500s you can’t do that. That’s why you want one auxiliary and one master. It’s the control of the master from the auxiliary that you need association for.
Walmart has a better price on it today