How can I prevent two Dell monitors to from mirroring in macOS?

For over a year I have been using a Macbook Pro (M1 2020) with two identical Dell P2419H monitors and a J5Create JCD543 docking station. Yesterday the HDMI port in the J5Create docking station failed and their support folks couldn't fix it. So I replaced it with a Belkin USB-C 11-in-1 multiport dock. My problem is that now the two Dell monitors work, but they're mirroring each other (displaying identical screens). One has a HDMI cable and one has a DP cable, and they're both plugged into the Belkin dock. When I go to **System Preferences** and **Displays** to fix the mirroring, it doesn't "know" I have two displays. Instead, it only shows one of the Dell monitors. Pressing the Alt button in **Displays** to go from **Night Shift** to **Detect Monitors** doesn't work. Nothing happens. Neither does the usual round of unplugging/plugging in the monitors and restarting. I also checked Privacy and Security to make sure that **Allow Accessories to Connect** is set on **Always**. I have the Belkin docking station plugged into one of the Macbook's USB C ports and the power cord plugged into the other. I suspect I may need to downgrade from Ventura 13.2.1 as others have reported similar problems, but I haven't found anyone with my EXACT problem. (If you're wondering why I chose the monitor/Macbook combination, I didn't; they were company issued.)