Use Hashes,

my @labels = ('1', '1', '1', '2', '3', '4', '5', '6', '6', '7');

my @seqs = ('a', 'ctgc', 'tggattgactgtg', 'atgcatg' , 'ctgctgcatgtgatg
+actgtg', 'tgatg', 'gtgt', 'gcgccggactatgattgagctagcgtatgctgcatgctgat'
+, 'gggtttttttttttccccccccccc', 'aaaaaagggggg');
for $i (0..$#seqs)
{
    $hash{$labels[$i]}.=$seqs[$i];
}
print "$hash{$_}\n" for sort keys %hash;
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