my $dst = "C:\\Users\\Administrator\\Desktop\\Perl_Scripts\\8312032_Security.evtx";
my $src = "C:\\Users\\Administrator\\Desktop\\Perl_Scripts\\8312032_System.evtx";

open (my $dsth, ">>", $dst)
  or die qq(can't open "$dst" for appending: $!);
open (my $srch, "<", $src)
  or die qq(can't open "$src" for reading: $!);

print {$dsth} <$srch>; 

close ($srch);
close ($dsth);