Why YSK: The granny knot is the most common reason as to why show laces seem to be undone so easily. It’s caused when the Starting Knot & Finishing Bow don’t “balance” each other. Recognizing this can help you make your shoe knots much more secure.
Edit: (BTW, YSK the website as well. It’s a really good resource for tying and lacing shoes)
Sometimes, I use this knot (without the extra twist on the bottom. It was once suggested on that site which must not be named, and for me, it does beat the double knot.