RMAN 11.2.0.2 Deleting Arch Logs That Do Not Meet ArchLog Deletion Policy

Hi DBAs:
This is a 3-node 11.2.0.2 RAC managed by ASM. Linux x86-64.  These are the non-default, RMAN configuration settings:

archivelog deletion policy to backed up 2 times to 'sbt_tape'
compression algorithm 'basic' as of release 'default' optimize for load false
controlfile autobackup on
controlfile autobackup format for device type 'sbt_tape' to '%f'
retention policy to recovery window of 29 days

I ran this backup command to sbt_tape this morning:
backup
  tag hotbk_VTL_01Apr2011_0730
  format 'al.%d.%h.%s.%p.%t'
  archivelog all not backed up 2 times delete input;

RMAN deleted all the arch logs even though not all of them had been backed up 2 times.  I confirmed the number of backup copies per thread/sequence in the catalog; view rc_backup_archivelog_details.