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