The double heart girl-love logo was designed by Spike, a poster here on Girl Chat, more than 20 years ago, which he used as a sig pic. He based it on the BL double triangle, with similar symbology. The large heart is a loving adult who protects a girl. The small heart represents a girl. The large heart is open to indicate the girl is free to leave at any time. Spike "open sourced" his design, and allowed anyone to use it for anything other than a sig pic on GC. Lindsay Ashford's website further popularized it.
Some BLers opened an online jewelry shop in Europe where you could buy necklaces and rings with the BL or GL logo.
Mainstream jewelry manufacturers started to sell it (either by coincidence or with plausible deniability) and called the design "winded hearts". (plural) That's the search term you'd use if you wanted buy jewelry with the GL logo. Jd420 is the one to ask about details here.
Strangely, a similar (but certainly not the same) double-heart ice cream logo started to be used around the same time Spike created his.
I don't think Spike gave it a formal name. You can call it GL Logo, Double Heart, Spike's logo, or anything you like. Call it Winded Hearts if you are shopping for jewelry.
This graphic, and jewelry related to it, seems to be memory holed on the internet. There seems to be no trace of it ever existing, and no, this is not a Mandela effect.