previous_word=
cat your_file |
while read word rest_of_line ; do
  print_word=$word
  if [ "$print_word" = "$previous_word" ]; then
    print_word="\t"
  fi
  print "$print_word $rest_of_line"
  previous_word=$word
done

while(<DATA>){
	my @tmp = split(" ",$_,2);
	if($.==1){
		$key=$tmp[0];
		print;
	}
	else{
		if(/$key/i){
			$tmp[0]=sprintf ' ' x length($tmp[0]);
			print join " ",@tmp;
		}
		else{
			$key=$tmp[0];
			print;
		}
	}
}
__DATA__
Maharastra Mumbai worli
Maharastra Mumbai navy
maharastra Pune
Maharastra Nagpur
Karnataka Bangalore
Karnataka Mysore
Karnataka Mangalore
Punjab Amritsar
punjab Jalandar

#!/bin/sed -f
	1h
	1!{
		x
		G
		s/\([[:alnum:]]\+\)\>.*\n\1\(.*\)/\t\2/i
		s/.*\n//
	}