I get that you can't buy the license and are trying to find another way, but what you configured right now is in no way a workable solution and probaly the cause that you are getting the multiple duplication jobs which then fail.
Stop using storage groups, that is not the way to go at it. There is no storage unit group which will give you multiple copies of the same data at the same time. That can only be done using inline copy. (which might actually be an option). DLP or Vault will not do this either, because they always work with duplication afterwards.
The straight forward way when you want a copy on disk and on tape is to use a DSSU (Disk Stage Storage Unit). This first writes to disk and then duplicates it to tape according to the set schedule. The copy on disk is retained as long as there is space to do so.
This means your copy on tape is always safe and listens to the options set in your policy and schedule (NOT your duplication schedule) but your copy on disk has no guarantees whatsoever.
You cannot use basic storage units in a Data LifeCycle Policy. Tape drives, advanced storage or Dedup is fine.
Personally, I think the only way to do what you desire by writing your own script. And scripting your duplication to tape. So do not make a DSSU but a DSU (Disk Storage Unit) and specify the desired (and possible) retention for the disk storage. Then, write a script which checks which images where written to it and have that script duplicate those to tape and then change their retention to the desired value.
A workaround would be to backup everything twice. With all the consequences that comes with it...(double or more time needed, is the data fast enough for the tape drive, multiple sessions, bottlenecks, tuning, etc. etc.). Personally, I cannot really recommend it because of issues that might arise with scheduling and such.
Basically, what it comes down to is that there are two options to achieve this functionaly. Spend a lot of time writing and perfecting a script, thus costing your hours, thus money. Or buy the options symantec has for this (DLP, Vault, etc.) and pay for those. But gain flexebilty now and towards the future and support when needed. ;)
p.s. If this is indeed a business requirment, personally I would feel it is THEIR problem and choice. No money = lower expectations, Give money = meet expectations. It is not your fault you need an option that costs money as a result of their demands. But that is my personal opinion, ofcourse.
