RMAN Delete Archivelogs Backuped twice

Following is an example based on RMAN 9.2.0.8.0 to backup archive log twice before purge from disk:

run {
allocate channel t1 type sbt;
backup archivelog all not backed up 2 times
format '%d_%s_%p_%U.arc'
tag 'iccs_arch_20081015';
delete noprompt ARCHIVELOG all backed up 2 times to sbt;
}