On an older version, before UUID's where introduced (5.0 used in example), create a custom template with name "Custom Template APP Solaris".
Export the template and try to import into 6.4.
It incorrectly matches built in template "Solaris by Zabbix agent":

As a result a template actually used in production might get items/triggers removed by accident.
It's probably related to this:
https://git.zabbix.com/projects/ZBX/repos/zabbix/browse/ui/include/classes/import/converters/C52ImportConverter.php#690
Which should apply upstream name changes to templates. But probably it's better to not do this than risk breaking existing templates.