I originally posted this problem (One Logitech Setpoint for two different Logitech mice? - Windows 10 Forums), but as I feel there's a new twist, it would be best to start a new thread.

Both my mice (M570 and M720) have the Logitech unifying mark on them, and there is a Logitech unifying dongle in place that was first being used by M570 with Setpoint. However, I found that Setpoint wouldn't recognize my new mouse (M720.) I then found Logitech's Options program (Logitech Options - Logitech Support) that offered more than Setpoint. DL'd Options, but it initially only recognized M720 and not M570. Using Options "add device," I kept getting "Try again" and haven't been able to get M570 to function on Options. No matter what I do, when Options is open, it only shows M720. Although M570 does function as setup on setpoint, I can't get to use setups for individual programs using Options??? All firmware is uptaded.