3 bit rand variable doing randomization for 8 times to get all possible values 0 to 7.
According to my calculation, total outcomes = 4096
80/4096 = 1.953125 %

But some values are getting repeated, I feel my probability/weightage calculation is incorrect. Could you please tell me what is the weightage to be used for all 8 values?

Randomizing a 3-bit number 8 times is 24 random bits: 2^{24} = 16,777,216 possible outcomes. 8! (factorial) = 40,320 of those outcomes do not have numbers that repeat. That means you have 99.97% chance of having a repeating number.

You only get the distributions you specify with the dist constraint as the number of randomizations approach infinity.