After each reboot of a client, Kea does see that the system did reboot and that it tries to get its lease back. So far so good.
But each of these result in a new lease (for the same IP and MAC) being shown in the Leases DHCPv4 section.
Screenshots attached.
Is that expected behaviour?
Fix coming in RC2
There won't be an RC2 this week after all. Either install the patch or wait for 24.1 next week
https://github.com/opnsense/core/commit/41b3881a73a53c60f03ccba3c6c3bbe8d20f8a8e (https://github.com/opnsense/core/commit/41b3881a73a53c60f03ccba3c6c3bbe8d20f8a8e)
opnsense-patch 41b3881
Take your time, no need to hurry :-)
I installed the patch and the lease duplicates are gone.