If a texture has an alpha channel, and that texture is painted on the surface of the terrain, glossy outlines appear. However, that does not seem to happen when the same texture, with the same settings is assigned once more. No matter how many same textures are assigned, only one of them will have the mentioned issue.

Steps to reproduce:
1. Open attached project
2. Open "SceneMain"
3. Select a third terrain brush texture
4. Paint on the terrain
5. Observe glossy outlines on the painted area

Expected result: No glossy outlines should be visible
Actual result: Painted area has glossy outlines
(Image attached)

Reproducable in: 5.5.1f1, 5.6.0f1, 2017.1.0a4
Note: version 5.3.4f1 does not load the project properly, 5.4.4f1 produces a crash when opening the project