FWIW, assigning the numbers to the arrays in separate lines makes no difference.

This is because your code's comments are wrong: 

# fill two 25 x 25 arrays with zeros, then modify a couple of cells
my @PP = my @OO = (1..25);

[download]

This does not create 25x25 arrays, this creates 1x25 arrays.

Below shows a 1x25 (what you have) vs a 2x5: 

use strict;
use warnings;
use Data::Dump;

my @one_by_twentyfive = (1..25); 
my @two_by_five = ([1..5],[1..5]); 
dd \@one_by_twentyfive; 
dd \@two_by_five;
__END__
[1 .. 25]
[[1 .. 5], [1 .. 5]]

[download]

or this one populates a 25x25 array, then overrides 3 slots:

<Reveal this spoiler or all in this thread>

In reply to Re^3: Array wierdness by pryrt
in thread Array wierdness by lgp

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