I don't think you can double-tie a hash. My first guess was that the second tie overwrites the first.

If you want to keep things in order, but can't find a tied hash that will work for you, keep a stack around, and push keys onto it as you add them to the hash. To get the keys out in order, just iterate through the stack.

That's probably close to what Tie::IxHash does internally, anyway. You're just stuck with the housekeeping.