If you want to put all of the the values for each key together, then give this a go.(I'm Assuming the file is in the above format.)

open (FILE,"c:/file.txt");
%hash=();
while (<FILE>)
      {chomp;
      split /:/;
      if ($hash{$_[0]}){$hash{$_[0]}.=",$_[1]";}
      else {$hash{$_[0]}=$_[1];}
      }
[download]