Strange error

[The chaser]

The error box says it... don't you see that you have "OnPickup" 3 times?

Go to the level editor. There should be a "CallbackFunc". There, put OnPickup_1 for key_laboratory_1, and OnPickup_2 for the key_2, etc. Ok, now, rename the functions according to the desired effect. I don't know what order do you want to achieve, so do what I said and, hopefully, it should fix it.