If I read you right, they wouldn't need the equivalent of 2 symbol identical 10 sided dice or 2 20's with repeats to generate an even distribution of random larger numbers, they could just have one die with their tens digit symbols and one with their singles. So if they wanted to D20's to generate 1-100 or 1-100 they just have 2 copies of each of the appropriate symbols on a die and presumably two of whatever passed for the analogue to zero, blank spot maybe. Say, one die alpha through theta? 2 of each plus 2 blanks, then another 10-90 2 each and 2 blanks and 100-900 2 each and a pair of blanks if they wanted to go that high.

So this die Joel referenced, can't be numerical, because 20 unique symbols on a die wouldn't mean anything to them, it would be gibberish, the first 20 unique math symbols would generate equal odds of 1-9, 10,20,30...90, 100, 200 that wouldn't serve any obvious purpose so they wouldn't be numbers.

Assuming that makes sense? It is, haha, all Greek to me.