You are making hard work of it. Modulus % is good for skipping N items and you can increment at the same time. You have $count and $count2 FWIW -> use strict to get told the error of your ways by Perl.

my $count = 0;
for my $input (@input) {
  next unless $count++ % 2 == 0;
    print "Got $1\n" if $input =~ m/DosID=(.{6})/;

}
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