My own phone number is now spam texting me 4 years ago
Owing to its unpopularity, or to which its unpopularity owes, Apple has only supported dual SIM for a few generations.
Curiosity: what are the use cases for two SIMs from the same country?
I have one line on Verizon and one on T-Mobile for better coverage, robustness to congestion.
iOS 13 has a "cellular data switching" feature for dual SIM that automatically chooses networks based on availability.
Data from one network even provides "WiFi calling" capability for the other line.