To reproduce:
1. Create new Unity project, create 2 lights
2. Make sure light have different baking method set (for example: one baked, one mixed)
3. Select both lights via Hierarchy window or Scene view, observe Inspector window

Expected: different properties through elements are marked with dash (-).
Actual: different properties through elements show the property value of the latest-created light (check picture attached)

Reproduced in: 5.6.0b2, 5.6.0f3, 5.6.2p2, 2017.1.0f3, 2017.2.0b2
Not reproduced in: 5.4.5p4, 5.5.4p1, 5.6.0b1
Regression starts in: 5.6.0b2

Note: from 5.6.0b2 on, the property is called "Mode" as opposite to earlier used "Baking"