You can create fast multikey sorting functions on the fly with Sort::Key::Multi:

use Sort::Key::Multi qw(nn_keysort) # the "nn" prefix means
                                    # to use two numeric keys

my @data;
while (<DATA>) {
   my @f = /([\d.]+)/g or next;
   push(@data, \@f);
}

my @sorted = nn_keysort { $_->[1], $_->[0] } @data;

printf("((%f %f) (%f %f))\n", @$_) 
   foreach @sorted;
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