Randomize - statement of language VBScript

Randomize uses number to initialize the Rnd function's random-number generator, giving it a new seed value. If you omit number, then the value returned by the system timer is used as the new seed value.

If Randomize is not used, then the Rnd function (with no arguments) uses the same number as a seed the first time it is called, and thereafter uses the last generated number as a seed value.

To repeat sequences of random numbers, call Rnd with a negative argument immediately before using Randomize with a numeric argument. Using Randomize with the same value for number does not repeat the previous sequence.