The if statement does work. But you are comparing (==) instead of assigning (=). Change your Statement to
if ($xOffsetSP !== $xOffsetMR){
            $xOffsetSP = $xOffsetMR;
            }
solved If-statement with !== is never true PHP
 
The if statement does work. But you are comparing (==) instead of assigning (=). Change your Statement to
if ($xOffsetSP !== $xOffsetMR){
            $xOffsetSP = $xOffsetMR;
            }
solved If-statement with !== is never true PHP