Static meshes exported from the engine have more vertices when imported back into the engine.
4.13 - 3172292 - YES
4.16 - 3466753 - YES
4.17 - CL3512142 - YES
Result: Vertex count is 1560
Expected: Vertex count is the same as step 2 (560)
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-46689 in the post.