Downloaded a few template files from the offical Zabbix repo, e.g. template_db_redis.yaml or template_app_opnsense_snmp.yaml.

Both from the 6.4 branch.

When I try to import them I get the template uploaded to the Zabbix server. So far so good. I confirm the dialogue 'Delete all elements that are not present in the import file?' with 'OK' and then I receive an 'Import failed', please see screenshot.

Root cause seems to be 'Duplicate entry '1766' for key 'PRIMARY'' in the valuemap_mapping table.

I've already checked the character set of the DB (is utf8mb4) and the open bug reports, maybe it is related to https://support.zabbix.com/browse/ZBX-21651.