NTAP_PM_RUN_BACKUP=Y means Snap Creator will kick off a secondary backup in protection manager after primary backup is done. You can schedule secondary backup through PM but if you are doing so you should set this option to NTAP_PM_RUN_BACKUP=N so secondary backup will only be done when PM schedule runs.
This is working as is intended. This is the way Protection Manager works, when it does snapvault update it will update for all new snapshots taken after last update.
Maybe a better way to do this is to turn off schedule in PM and set RUN_PM_BACKUP=Y this would make it so SC triggered PM to do backup right after snapvault is done. Another option if it is desired to NOT snapvault certain backups, create two configs 1) without PM setup 2) with PM setup.
One thing i think you can do is use different policies so hourly and daily. When SC runs PM backup schedule NTAP_RUN_PM_BACKUP=Y or if you run backup form PM you select a retention type: hourly, daily, weekly, or monthly. It is my understanding that PM will only do updates for snapshot within a given retention. So if you have 10 new hourly snapshots then PM will update 10 but if you have 10 hourly and 10 daily and choose hourly as policy it should only update 10.
I would open a case or ask the PM community about this. It sounds like a PM issue, since SC is sending the retention type, PM should not be vaulting retentions which dont match the retention type. This in my opinion is a design flaw or a bug.
In the short-term I hate to say it but only way to do this is to not use PM and use SC to do snapvault. SC will only vault 1 snapshot, the one being taken and only vault the snapshot which matches the correct retention. I know this is less desired than using PM but maybe this would provide a gap solution until PM can support this?
Snap Creator only registers the snapshot it has nothing to do with snapmirror or the snapmirror update that is Protection Managers problem.
SC does register retention type. Just run with the --debug argument or look in log file. Search for "retention-type" this is where SC creates a backup version in PM and you will see here it is whatever you have set for --policy. The only valid arguments are: hourly, daily, weekly, monthly, or none.
If there is something we can do better on SC side let me know. I have looked at API documentation so it appears we are doing everything correctly.