Can Passbeam put different people on different VLANs?

Yes, by Entra group. Rules are checked in order and the first match wins, so someone in two groups always lands where the page says.

Managed devices are placed by their Entra device group, because their certificate is the device's and has no user. A shared laptop gets the same VLAN whoever is using it. BYOD devices are placed by their owner's groups, because their certificate is in the person's name. See “How do I set up BYOD so users can add their own devices?”.