Just a slight modification to Peter's answer
Use RandomInt but if you want a 50% split just Random to 1, so that is binary, 0 or 1, if 0 go to A if 1 go to B, rather than dealing with all the numbers in between 0 and 10.
Or if RandomInt isn't to your liking, use modulo (%) eg Second(GetCurrentDateTimeUtc()) % 2 - this will get the current seconds value of the date time and return either a 0 or a 1.
Either option will work fine, and you can change the percentage split by changing the Random or % value and then accounting for the extra values
eg Random 3 - 0-1 go to A 2 go to B. which is effectively a 2/3,1/3 split etc.
------------------------------
Anton Vroon
------------------------------