if there is any wear on the caliper rails your pads slide on, the anti rattle clips won't make good contact...check for wear and or grooves.
original anti rattle clips are made of spring steel and you can't bend them
Well, i have to disagree with you a little bit here.
Yes, if you have original pad hold down clips, there isn't any reason to bend them.
But, i have had occasions that i have had to "bend" a few back into shape due to neglect, or being bounced around for years and years in storage.
They can be bent, no problems, never had an issue doing it.
It's the modern reproduction ones that aren't bent right, out of the box, that you have to make right.