A good analogy would be our two good (insert tongue in cheek, here) Presidential Candidates in the US. They are traveling from place to place giving basically the same speech, and maybe tweaking it from time to time, although the message is rather consistent (that message being the other guy lies, usually).
Jesus gave his Sermon on Salvation through Galilee and Judea with a similar message that was probably changed a little here and there. Notice, one is “on the Plain” and one is “on the Mount” which would indicate different speeches.