not every bitcoin private key has exactly 2 hex characters of each digit...so for most private keys there is going to be one hex character at least one that appears more than the others. whether that came about through a biased dice or a random number generator on a computer, you would have no way of knowing.
What does this have to do with
anything? A private key in which one character appears more than once doesn't make it less secure than one which doesn't.
that's exactly the point I was trying to make. along with the fact that if I give you some 32 character HEX string where one HEX symbol appears more than 2 times, you don't have anyway of knowing what caused that to come about - be it just a random happening or something that was caused by a bias towards that particular hex digit.
It can, but it is significantly more complicated. Essentially you would roll the dice three times, and make a note of all three numbers. If any number is repeated, you discard the rolls and start a new set of three.
Interesting but it seems like that would basically multiply the number of rolls required by at least a factor of 6. that's a bit unrealistic to force someone to roll a dice around 600 times just to generate a single bitcoin private key. the chances they make a mistake at some point are high. maybe a way to shortcut that process would be to take 3 dice and roll them all at the same time.