# build hash
while() {
...
$hshFoo{$key1}{$key2} = $strFileName;
...
# key1 is a number
# key2 is a sequential number
}

##</code><code>##

$hshFoo{2823}{0} = 2823_0.xml
$hshFoo{2823}{1} = 2823_1.xml
$hshFoo{2823}{2} = 2823_2.xml
$hshFoo{2823}{3} = 2823_3.xml

##</code><code>##

    foreach $key1 (keys %hshFoo) {
        foreach $key2 (keys %{$hshFoo{$key1}}) {
            print "$key1/$key2 => $hshFoo{$key1}{$key2}\n";
        }
    }

...
Output:
2823/1 => 2823_1.xml
2823/0 => 2823_0.xml
2823/3 => 2823_3.xml
2823/2 => 2823_2.xml
...
I expected:
2823/0 => 2823_0.xml
2823/1 => 2823_1.xml
2823/2 => 2823_2.xml
2823/3 => 2823_3.xml