There is a ton of similarity between this hash and a symmetric matrix. So, the choice of which symmetric element to be the right one and the reversed one is arbitrary. Since the indices are alphabetical, then alphabetical order makes the most sense. Use the alpha pair where the first letter is earlier in the alphabet. ikegami's solution below seems to do that nicely.

In reply to Re^2: confused with a hash which contains reversed keys by dwm042
in thread confused with a hash which contains reversed keys by Anonymous Monk

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