c:\@Work\Perl\monks>perl -wMstrict -le
"my ($ID, $ID2, $mac2) = ('foo', 'foo', '');
 ;;
 if($ID eq $ID2 and $mac2 eq ''){
   print 'true block';
 }else{
   print 'false block';
 }
"
true block

c:\@Work\Perl\monks>perl -wMstrict -le
"my ($ID, $ID2, $mac2) = ('foo', 'foo', '');
 ;;
 if($ID = $ID2 and $mac2 = ''){
   print 'true block';
 }else{
   print 'false block';
 }
"
false block