How to reproduce:
1. Open the attached "SliderBug" project and "Repro" scene
2. Click on the "GameObject" in the Hierarchy and open Inspector window
3. Notice that it has slider, change the value of slider (remember the previous one)
4. Undo the change (press CTRL+Z or Edit --> Undo Inspector)

Expected result: Value is changed to the previous one
Actual result: Value is incrementally changed, meaning that you need a dozen of UNDO's before reverting to previous value

Regression introduced in - 2017.3.0b6, 2017.2.0p1, 2017.1.2p2
Reproducible with - 2018.1.0a5, 2017.3.0b10, 2017.3.0b6, 2017.2.0p2, 2017.2.0p1, 2017.1.2p3, 2017.1.2p2
Not reproducible with - 2017.3.0b5, 2017.2.0f3, 2017.1.2p1