Adding arrays to multi-dimensional array within loop
This is because array_merge is not the right operation for this situation. Since all the $playerdata arrays have the same keys, the values are overridden.
You want to use array_push to append to an array. This way you will get an array of $playerdata arrays.
array_push($allplayerdata, $playerdata);Which is equivalent to adding an element with the square bracket syntax
$allplayerdata[] = $playerdata;
This will add the second array to the first array: A merge is something different.
$allplayerdata[] = $playerdata;