I could have sworn there was already a module to do this, but I could be mistaken.

Maybe you were thinking of Tie::IxHash to receive the keys in the order the elements were inserted into the hash. From the Cookbook (recipe 5.6):

use Tie::IxHash;
tie %HASH, "Tie::IxHash";
# manipulate %HASH
@keys = keys %HASH;         # @keys is in insertion order
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-- Hofmator