open(FILE, "<", name.ext") or die("couldn't open file: $!");
open(OUT, ">", new.ext") or  die("couldn't open file for writing: $!");
my $cmp = <FILE>;  # the first line
print OUT $cmp;        # is always unique
while(<FILE>) {
	if ($_ ne $cmp) {    # current line unlike last one?
		print OUT $_; # print it out
		$cmp = $_;   # current line new reference
	}                         # otherwise ignore
}