Did a quick search for padded clips, and couldn't find the exact clips in your pic. However, I did find these other similar things. Maybe something will help.
Covers for snap clips, with instructions on how to attach to your own clips. If you're crafty, you could probably use a similar procedure with duckbill clips.
SNAP CLIP COVERS - Home
Pages selling duckbill clips suggest using grosgrain ribbon the same width as your clip for an inside lining. Apply with hot glue.
48pc Silver Single Prong 1.8" 45mm Hair Clip (L97)
Also, here is an Etsy listing for a duckbill clip lined with ribbon. Looks like it was simply hot glued around the handle bit and over and around the top part of the clip that would show when wearing:
Hair Clips Barrettes Heart Hair Clips Valentines by BabySmooches