myarraysize=20;
images = new Array(myarraysize);
for (i = 0; i < myarraysize; i++) { images[i] = "<IMG SRC='images/" + (i+1) + ".jpg' width='240' height='180' border='0'>";}
index = Math.floor(Math.random() * images.length);
do {index2 = Math.floor(Math.random() * images.length);} while (index2 == index);
//do {index3 = Math.floor(Math.random() * images.length);} while (index3 == index || index3==index2);
document.write(images[index] + images[index2]); 
//+ images[index3]);