Select Random User From Multiple Selectboxes?

I have a script which allows me to select random users from one select field to another and works like a charm, but... I want to be able to get random users from one select field to multiple (lets say 2) other select fields...

So lets say that I have 5 users in the first field (select1):
James
Bill
Jennifer
Bob
Karen

Now when I press a button:
<input value="" type="button" onClick="randomusers();" />
2 users a moved to select2 and other 2 users is moved to select3.

My current script is as follows:
Code:
function randomusers(){
var given = 2, used = {}, randnum, opts = $('#select1 option'), olen = opts.length, hiddiv = $('#hiddendiv');
function ran() { // generate a unique random number
random = Math.floor(Math.random() * olen);
return used['u'+randnum] ? ran() : randnum;
} for (var i = 0; i < given; i++) { // get the correct quantity of randoms
used['u'+ran()] = true;
} var players = opts.filter(function(index) { // remove all options that are not one of the randoms
return !!used['u'+index];
}).appendTo('#select2');}