I agree that some clarification is needed. If this is just for a lookup table there's no need to randomly duplicate data, as you can just have a lookup table with an integer key and have the outside code that does the lookup use a rand() or some other function to derive a random entry from the table.
I'll wait for some more explanation, too.
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echo S 1 [ Y V U | perl -ane 'print reverse map { $_ = chr(ord($_)-1) } @F;'