Google Messages has been working on dual SIM RCS since the start of this year, and support is now more widely rolling out in beta. To date, you could only have RCS active on one phone number at a time in Google Messages. Dual RCS support lets both be active simultaneously. Going to Settings > RCS chats notes the status of both as “Connected” with checkboxes to disable/enable each SIM. After testing in recent months, a lot more users are seeing this with the latest Google Messages beta (version 20241018_01_RC00+) in recent days, with another rollout today. There are more than a few reports in the US on Google Fi, T-Mobile, Verizon, etc. across various phone models, including Samsung. You can have both a physical SIM and an eSIM instead of needing variant hardware. However, not all Google Messages users report having dual SIM RCS support yet.