How to fix overlapping materials? I was following along with Blender Guru's tutorial on this Chair here, and I got to the point where he begins the UV unwrapping section. I was doing fine until I noticed that once I applied the material, the back of the chair leg now has this overlapping of the material. I heard it is called Z-fighting. I moved the vertices over each other, and away from each other, but no luck. Merging doesn't do anything. When I alt-click, both vertices are selected.



The line goes across the whole leg here.



I have tried moving the seams, adding more, removing some, but the problem persists. Also tried to merge by distance, which does work, but not entirely. Some parts of the leg do no overlap, but the rest of the mesh, such as the bottom half of the leg, still has the problem, except this time it is warped. 

Here is where it overlaps.


There is this thing over here as well.


I've looked online, and didn't find much of what I was looking for. There were either different solutions for different shapes, or none at all. I was really invested in the tutorials and had fun moving along, but this wall is starting to bug me, and I would like to figure this out
EDIT: Here is the file: http://www.mediafire.com/file/6ulfx6lrcwbisaa/chaircopy.blend/file

Thank you
You have non-connected edges and faces overlapping, I guess your problem comes from that, you need to correct this: Delete the faces loop, use the Bridge tool to reconnect the edges, mark seam again and unwrap.