One of my children received a second check; another didn’t, and my wife and I also didn’t (after we had all received the initial ones). We haven’t received the forms you’re supposed to receive either, which would be needed to file taxes (we’d get a credit for the missing payment).
I didn’t get a form, but H&R Block ones I got 1200, but not the 600. How they knew? Have no idea. But the information they had was correct and they took the 600 off the taxes owed. Nice!