In the attached videos, the line of the fishing rod seems to multiply when you have the use item key held for a prolonged amount of time (I have it as a key on the keyboard, idk if the same effect happens on the mouse). I'm not sure if this is only a visual glitch because when you try to reel in any of them, you can only interact with one. However, when in water, the entities still seem to be there because the hooks bob when they need to.

(In the fishing rod in water picture, I can only interact with the line on the left but the others can still bob/catch.)