1 BEGIN {

     2     previous="";

     3     prefix="";

     4     ORS="";

     5     OFS="";

     6 } 

     7 {

     8     if ($1 != previous) { 

     9 	if (previous != "") {

    10 	    print "\n\n";

    11 	}

    12 	previous = $1;

    13     	print $1;

    14 	prefix="\t";

    15     }

    16     print prefix $2;

    17     prefix=" ";

    18 }

    19 END {

    20     print "\n";

    21 }