Steps to reproduce:

1. Import 'RabbitMQ by HTTP Custom TAG.existing.yaml' Template
2. Import 'RabbitMQ by HTTP Custom TAG.new.yaml'. Zabbix will show new Discovery rule with Prototypes to be added.
3. Zabbix report 'Imported successfully' however new Discovery rule is not added
4. Repeat 2-3. Everytime Zabbix will show new Discovery rule with Prototypes to be added, but will not add it.

I tested it on two different servers, both 6.2.6

Result:

On every import, Zabbix shows that new items will be added but doesn't add them. See the video. In the attachments you can find the existing template and the template with changes.

Expected:
Changes to the Template are applied and saved.

I added in the same way the existing 7 rules, but Zabbix doesn't want to add the 8th rule for some reason.