The old (callback) functions have nothing to do with the error i guess.
Just for clarify:
If i'am talking about functions in this case, i mean the callback function which is executed if the button is pressed, something like this:
getnode("Label").set_text("button is pressed")
But that this could happen during your program is running, you'll have to say if which button is pressed and then execute which part of code(the callback function).
So this could be done within the IDE and the Node/Signals. Or you do this in your code, something like:
That means get the buttonnode and connect it with the function "on button pressed".
Execute its code when the buttonnode is pressed."self" means that the .connect method and the Callback are in the same Script/Class.
Back to the error: it says: hey, there are two times a button connected with a callback, what is obviously not necessary ( and some more connections like release and so on)
If you wanna do more than one thing after a button is pressed you' have to do it like: