What is going on? Two copies of a texture on one face of a prim?

[Jennifer Boyle]

I have some steps that I built many years ago from prims. I noticed a defect recently which I first thought was due to an extra prim being in the steps. When I investigated, I found that one face of one prim was behaving like two faces or two prims. There were two distinct areas, and in each, the texture was aligned differently from the other. The other faces es of the prim are normal. Can anyone explain what is going on? Here is a photo:

 

[Ardy Lay]

It is path cut.

[Jennifer Boyle]

25 minutes ago, Ardy Lay said:

It is path cut.

Thanks. That is exactly right.