Hi
Physical tape drives can be shared with multiple netapp controllers, but DMA (backup appliation) should have license to use the shared tape drives for backup.
like "Shared Storage Option license" in netbackup
https://www.veritas.com/support/en_US/doc/24437881-126559615-0/v95675450-126559615
backup application vendor would provide you more details on these options.
let us know if this answers you query?.