Was testing this AE expression to randomize the frames, and came up with this...

seedRandom(1,true);
var t=timeToFrames();

var r1=-3;
var r2=-2;
var r3=-1;
for (var i=0;t>=i; i++) {
var r3=Math.floor(random(120));
if (r1==r3 || r2==r3) {
t++;
continue;
}
r1=r2;
r2=r3;
}

framesToTime(r3);