Alternatives:

my %h;
$h{$_->[0]}[0] = $_->[1] for @a1;
$h{$_->[0]}[1] = $_->[1] for @a2;
my @arr = map [ $_, $h{$_}[0], $h{$_}[1] ], sort keys %h;
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# Nevermind, this is broken and not worth fixing.
my %h1 = map @$_, @a1;
my %h2 = map @$_, @a2;
my @arr = map [ $_, $h1{$_}, $h2{$_} ], sort keys %h1, keys %h2;
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If you were dealing in hashes instead of arrays:

my %hash = map { $_  => [ $h1{$_}, $h2{$_} ] } keys %h1, keys %h2;
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