To reproduce:

1. Open the project, attached by tester (lightmapDefines.zip)
2. Open "testScene" scene
3. Press Play
4. In Frame Debugger, find Draw Mesh Sphere call in tree view.
5. Observe Keywords

Expected: either LIGHTMAP_ON or LIGHTMAP_OFF is defined, but not both at the same time
Actual: LIGHTAMP_ON and LIGHTMAP_OFF are both defined at the same time

Reproduced in 5.6.1f1, 2017.1.0b6
Did not reproduce in 5.5.3p2
Regression introduced in 5.6.1f1