The test data the OP has doesn't reveal the difficulty well. A better test (I've gotten rid of the extra array parts to focus on the sorting) is:

use 5.010;
my @items = qw/ A1a1 A1a12 A1a2 A10a1 A12a1 /;
say join " ", sort { $a <=> $b } @items;

# prints: A1a1 A1a12 A1a2 A10a1 A12a1
#                ^- :( -^
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