png transparent removed when merge 2 image in php - php

Question

I have below code,I want to merge two png file,both of them has transparent part,
file 1 :
and file 2:
and the output png file is
I also try to uncomment
//imagealphablending($src2, false);
//imagesavealpha($src2, true);
//imagecolortransparent($src2, 2130706432);
but not work, where is the problem?
$background2=imagecreatefrompng('avatar_blank_big.png');
$dest2 = $background2;
$toyitems2 = array(
'cloth-1763-1249' => 'cloth-55e.png',
);
foreach ($toyitems2 as $i => $item) {
$src2 = imagecreatefrompng($item);
if (!$src2) continue;
//imagealphablending($src2, false);
//imagesavealpha($src2, true);
//imagecolortransparent($src2, 2130706432);
$src_x = imagesx($src2);
$src_y = imagesy($src2);
$list = explode('-', $i);
//var_dump($list);
imagecopymerge_alpha($dest2, $src2, intval($list[1]), intval($list[2]), 0, 0, $src_x, $src_y, 100);
imagealphablending($dest2, true);
imagesavealpha($dest2, true);
}
header('Content-Type: image/png');
imagepng($dest2);
function imagecopymerge_alpha($dst_im, $src_im, $dst_x, $dst_y, $src_x, $src_y, $src_w, $src_h, $pct){
// creating a cut resource
$cut = imagecreatetruecolor($src_w, $src_h);
// copying relevant section from background to the cut resource
imagecopy($cut, $dst_im, 0, 0, $dst_x, $dst_y, $src_w, $src_h);
// copying relevant section from watermark to the cut resource
imagecopy($cut, $src_im, 0, 0, $src_x, $src_y, $src_w, $src_h);
// insert cut resource to destination image
imagecopymerge($dst_im, $cut, $dst_x, $dst_y, 0, 0, $src_w, $src_h, $pct);
}