you could use "scalar" to get how many matches were returned by =~ into a @matches array....

while (<DATA>) {
    chomp;
    my $s = $_;
    @matches = $s =~ /(\w)\1/g;
    if (scalar @matches == 3) {
        print "$s: three two-letter repeats.";
    }
}
__DATA__
hullaballoo
chubbalicious
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