Just trying to figure out what phones actually offer dual SIM in the USA. I bought a Samsung dual SIM off Amazon only to return it because the second slot was inactive.
Welcome to Android Central! Are you sure the 2nd SIM was inactive, or was it just that it didn't support your carrier's network bands? On older dual SIM phones, the 2nd SIM slot is often only good for 2G (i.e., for phone calls only), and most US carriers have shut down their 2G networks.
I bought on here a Teracube 2e from another member that was practically new. It has true Dual-Sim and performs well on T-Mobile for me as backup network device.
It's not the flashiest or the quickest but I think new, they're around $200 USD so it's one I can think of.