Review on Android Tablets Keyboard Certified Metallic by Jonathan Abreu

I bought 2 new T-Mobile SIM cards for the tablet. I installed them and turned on the tablet. It only recognizes the SIM card in ONE slot. I changed the SIM cards in the slots and turned it back on. It still only recognizes the SIM card in the ONE slot. The SIM card in slot 2 is NOT recognized. Is this tablet defective? Why TWO SIM slots? What is the second slot used for? I can't find any instructions for it online. Should be able to download the manual but no. Also, if you use Bluetooth port C to use a wireless mouse, you can't use it for anything else, e.g. B. an external drive or flash drive or an HDMI connection for streaming to a TV.