think of it this way... if you promise your friend Thomas that you will wear a red shirt tomorrow, then you later promise your friend Michael you will wear a red shirt tomorrow, do you have to wear two red shirts?
no.
It's the same with interfaces. you're promising to implement a method, you're just promising twice.
The two methods with the same signature must have the same intent in their respective interfaces,
Campbell, we're gonna have another disagreement. I think "must" is too strong a
word. "Should" or "Hopefully will" i think would be better. nothing forces them to be similar - it is not a requirement.
Now, if they don't, you're gonna have problems somewhere, but 'must' is just not a word i would use to describe this.