Ultimaker Cura is adding redundant top/bottom layers
It would appear that your model does not conform properly to STL standards. I base this conclusion on a couple of factors. When I loaded the model into Simplify3D slicer, it displayed fine, but when sliced, displayed nothing. Using the onboard repair feature, it presented the entire model as being composed of non-manifold surfaces.

Meshmixer's Analysis/Inspector feature also highlighted the entire model as flawed.

Another observation is that there is an extraordinary amount of facets/triangles/faces to this model. Nearly three-quarters of a million triangles for something that should be much simpler.

The most recent version of Prusa Slicer 2.0 presents an error message indicating that no layers were detected. This is peculiar indeed.

All of the above points to a problem with the source file or the software used to create it.

Please consider to add to your post the program you used or the source of the model.