We are currently tracking an issue where two or more DSLR cameras of the same model are not connecting to Ecamm Live on macOS Sequoia when connected via USB.
Our engineers have looked into this issue extensively and have determined that recent changes in macOS Sequoia have made it impossible to resolve the issue on our end. We’ve submitted a bug report to Apple, but unfortunately, we cannot guarantee a fix at this time.
Note that a single DSLR camera will still connect via USB.
In the meantime, here are some potential workarounds:
Use an HDMI encoder (such as an Elgato Cam Link or similar device) for each additional camera of the same model to avoid the connection conflict.
Downgrade your macOS to the previous version, Sonoma.
Use alternative camera models that are not affected by this issue.