unit 53 {
            description 1234-rwan-1;
            vci x.yy;
        }
        unit 54 {
            description 45ff-rwan-1;
            vci x.yz;

##</code><code>##

	#                         $1        $2
	while( $file =~ m/^\s+description\s(\w\w\w\w)(-\w+-\w+);/gm ) { 
		#say $1, $2 if $opt{debug};
		# Way to reset $1, $2, etc?

		my $prefix   = $1;
		my $suffix   = $2;

		my $old_name = $prefix.$suffix;

		if( $old_name ~~ @old_names ) {   # Should only be processing each name once!
			say "ERROR: Already processed old_name $old_name.";
			reset;
			next;  #<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< NEXT
			}
		push @old_names, $old_name;

		my $new_name = my_rand(); # Update: my_rand now takes care of duplciates

		my $new_full_name = $new_name.$suffix;
		say "Replacing $old_name with $new_full_name..." if $opt{verbose};
#		$file =~ s/$old_name/$new_full_name/g;
		reset;
		}

##</code><code>##

Replacing 572l-rwan-1 with 4S1O-rwan-1...
Replacing 25hu-rwan-1 with 9L8O-rwan-1...
Replacing 51h2-rwan-1 with 2PDZ-rwan-1...

##</code><code>##

Replacing 7301-rlab-b3f2 with 8SF6-rlab-b3f2...
Replacing 8SF6-rlab-b3f2 with CAB7-rlab-b3f2...
Replacing CAB7-rlab-b3f2 with 3X7L-rlab-b3f2...