ref: 58fa29447b845f91dfc2a6734f525ed47375393b dir: /sys/lib/man/permind/dup2.awk/
$NF!=lastf2 {if(last2!="") print last2 lastf2=lastf1; last2=last1; lastf1=$NF; last1=$0} $NF==lastf2 {print} END {print last2; print last1}