Here is a photo of sock and garter clips with a red arrow pointing to the one most resembling the dug example.
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I'm about 99% sure the one the red arrow is pointing at is actually a cape hook, or cape clasp, and is supposed to be bent like that.
The one in the OP is indeed a garter belt clasp.
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Not to be argumentative, but those garter clips shown in your photo are completely different than the one the OP posted.
I just used the photo as an example, I wasn't trying to match it to that particular garment and manufacture. Obviously it's much older.
Sometimes folks are a bit too focused on finding an exact match with patent and serial numbers, but unfortunately sometimes all you can get is 'close enough'.