Hi,
I'm making some UI with tk2d and used some Checkbox prefab from tk2d to do so. What I do is I check if the Checkbox's GetComponent<tk2dUIToggleControl> ().IsOn is true, I do something then toggle it and by default when the game starts, all the buttons are ON.
Problem is, when I click on these check boxes that are duplicates of each other, in OnClick event, 2 of them report IsOn as False and 3 of them report it as True.
What I assume is that somewhere in tk2d, they are first toggled off and then my OnClick event handler runs but for 3 of them, I first get the Onclick event handler then tk2d (or Unity) takes control and sets it off.
Check thise scene:
https://www.dropbox.com/s/n4s2mifi0os7507/shop.unitypackage(It doesn't have your package)
And check the OnClick event for first button and 2nd button from the left for example. In ShopController.cs file, in Toggle_Equip_Of_PowerUp_1_Click if you put a debug.log you can see that it returns True for IsOn and it's good and what I expect it because in the scene it's toggled true for Is On but the second button from the left's Toggle_Equip_Of_PowerUp_2_Click returns false for IsOn check.
Hope it shows the same behavior on your system as well.
Let me know if you have problem reproducing it.
Best.