Backup policies with multiple retention levels

Frequency based backups are your best shot. and yes, they do not trigger 2 schedules same time.and when the 2 scheduls are overlapped.. it will tirgger the fist one which one has the longer due.

however when you have a fixed months to trigger the longer retenctions.. calender based schedules can do that better way..

you can configure these longer retenction backups in seperate policy and rest all in another policy.. (do make sure these 2 policy schedules are not overlapped.)

see the below artical to understand the frequency based backups from experts hand

https://www-secure.symantec.com/connect/articles/netbackup-frequency-based-scheduling

It sounds like you could accomplish this with two Schedules, one with the first retention period and a second with the longer retention period.  I don't think you can make this happen without using the Calendar Schedule type.

Just out of curiosity, why would you want two of the backups kept for two years and the third backup longer?  Are you talking about backups of different sets of data or is this all one policy?  More information would make it easier to give the best advice.