“Also, “You are my sunshine” and “This land is your land” use the same tune. As each other, I mean. “
I disagree- they start out the same – and both use lots of C,D,E and Fs. But they are different- an obvious difference, the high note of “happy” in the former song is not found in the latter.
To prove it, here are the actual notes for both songs in key of C (sorry can’t put in the length of notes, dashes indicate longer beats)
This land:
CDE F-F– FCD E-E– CCE D-D– DDCD E-E– CCDE F-F– FFCD E-E– DD-CBBCD C–
And now for sunshine:
GCD E-E- E#DE C-C- CDE F-A- AGF E– CDE F-A-AGF E-C- CDE-FDD EC-
But here is another pair that I found is the same tune- the high parts of Avraham Fried’s (I think) “ki hamitzva hazos” starting from “ki korov eleicha hadavar me’od…” and “zacharti lach chesed neurayich” starting from “lechtech acharai bamidbar…” They have different tempos/keys, but they are very very similar.