Array Help

Below is what I have. Is there anyway to put this in an array so that each items value can't be the same?
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<SCRIPT LANGUAGE="JavaScript">
<!--
function testSelect (form) {
Item1 = form.ranking1.selectedIndex;
Item2 = form.ranking2.selectedIndex;
Item3 = form.ranking3.selectedIndex;
Item4 = form.ranking4.selectedIndex;
Item5 = form.ranking5.selectedIndex;
Item6 = form.ranking6.selectedIndex;
Item7 = form.ranking7.selectedIndex;
Item8 = form.ranking8.selectedIndex;
Item9 = form.ranking9.selectedIndex;
Item10 = form.ranking10.selectedIndex;
Item11 = form.ranking11.selectedIndex;
Item12 = form.ranking12.selectedIndex;
Item13 = form.ranking13.selectedIndex;
Item14 = form.ranking14.selectedIndex;
Item15 = form.ranking15.selectedIndex;
Item16 = form.ranking16.selectedIndex;
Item17 = form.ranking17.selectedIndex;
Item18 = form.ranking18.selectedIndex;
Item19 = form.ranking19.selectedIndex;
Item20 = form.ranking20.selectedIndex;
Item21 = form.ranking21.selectedIndex;
Item22 = form.ranking22.selectedIndex;
Item23 = form.ranking23.selectedIndex;
Item24 = form.ranking24.selectedIndex;
Item25 = form.ranking25.selectedIndex;
Item26 = form.ranking26.selectedIndex;
Item27 = form.ranking27.selectedIndex;
Item28 = form.ranking28.selectedIndex;
Item29 = form.ranking29.selectedIndex;
Item30 = form.ranking30.selectedIndex;
if (Item1==Item2) {
alert("RANKINGS CAN'T BE THE SAME FOR 2 DIFFERENT PROPOSALS!nnPlease reselect a different ranking other then what you've already used.");
return false;
}
}
//-->
</SCRIPT>
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Thanks
Todd