I tend to view digressions like that as a way in which a thread is kept going in the hope someone will turn up with an answer.

But the point Jim made is valid, about the fact an image appears in different places shouldn't be used as proof one inspired the other. Often that kind of thing does tend to be assumed, more especially with tunes.

After all, the fact that our eyes are remarkably like the eyes of an octopus isn't proof we are descended from octopi, or they from us.

But the lines

She is just like a bud of rose,
That blooms in the month of June.
Or like some musical instrument,
That's just been lately tuned.

Are pretty evidently related to

My love is like a red, red rose
   That's newly sprung in June :
My love is like the melody
   That's sweetly played in tune.

Though whether the former is based on the latter, or both come from some earlier source is not completely certain.