In \applications\downloads\modules\front\downloads\view.php around lines 1023-1028 there's a duplicate $existingThumbnails = array(); line (3rd and 6th):

			$existingRecords = array();
			$existingScreenshots = array();
			$existingThumbnails = array();
			$existingLinks = array();
			$existingScreenshotLinks = array();
			$existingThumbnails = array();