Algorithm rollover is blocked if there is a keytag conflict

Test failure here: https://gitlab.isc.org/isc-projects/bind9/-/jobs/4651551

This happens when there is an algorithm rollover with two the same keytags, one for each algorithm. There is a genuine bug in the code when looking if a key matches a certain key state that won't match if we select the wrong key (with the same keytag).