The way I like to do it is ignore the FRAG lines, as I'm usually only
interested in the IMAGE lines to grab the images on the media set.

So, I do the following:

./bpimmedia -l -mediaid abc123 | awk '/IMAGE/ { print $4 " - "
strftime("%m/%d/%Y",$11) }'

that should print out the backup/image id (space delimited column 4 in
the raw bpimmedia output) and a good formatted date/time (column 11)

the /IMAGE/ at the beginning filters out the FRAGs and keeps only the
IMAGE lines