If two people design keys for the same organisms, they will probably be similar. Which details of the two keys must be IDENTICAL.

The order of the questions my vary, but those questions should be worded exactly the same way.

They should have different numbers of questions.

The questions should be answered in the exact same order.

They don't need to be identical. The only thing that makes a key "right" or "wrong" is whether or not it can be accurately identify all the things that the user will encounter in their environment.