Steps to reproduce:
1. Download and open attached project
2. Open scene "test"
3. Hit play
4. Hit play again to stop
5. Click on "TestGameObject" in the hierarchy view
6. Observe console logs

Note: there is a script set-up (TestEditor) to write a debug message when selecting an object in the hierarchy view(onEnable and onDisable).

Expected result: 1x debug message Enable and 1x debug message Ctor when selecting, 1x debug message Disable when deselecting
Actual result: multiple of the same Debug messages are shown

Reproduced on 5.4.1p3, 5.4.2f1, 5.5.0b9, 5.6.0a1
Regression found in 5.3.6f1
Bug first appears in 5.4

Note: after importing the project into 5.3, saving and opening it back in 5.4, the bug seems to dissapear