I stumbled across it and I saw it in a showcase. I couldn't recognize it. It looks like it's a way to tie fixed loops in the middle of a rope.
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It's undoubtably a slip knot that's been tied off with a half hitch. some of the knots look different because some are tied off right-handed while others are left-handed. Compare the image below to the second image in the question:
I think I even know why that knot was used in that display case too. Whoever made that display and tied the knot is obviously artsy or crafty, and probably crochets. When you start a crochet you tie of your yarn to the hook with a slip knot.
Imagine the picture below with the tail end tied off with a half hitch:
I don't know what's being hung in the display case, but the same person probably pre tied the overhand knot in the rope to mark how high to hang whatever it is they're hanging, then wrapped the tail end around the bar, fed it through the over hand knot, snugged it up the the bar then quickly tied off the tail with a half hitch.
They are examples of a round turn and two half hitches. Sometimes known as an anchor hitch or a fisherman's hitch.
A Useful Boating Knot: A Round Turn and Two (or more) Half Hitches (ABOK # 1720, p 296) is useful for attaching a mooring line to a dock post or ring although probably less secure than the Anchor (Fisherman's) Hitch.