Manipulate a list representing Bach's Prelude in C

This is a perfect application of a user-defined function:

chorale[x_] := {x, x[[3 ;; 5]], x, x[[3 ;; 5]]} // Flatten;

Then you can form the complete piece by mapping the function over the data bwv846:

chorale[#] & /@ bwv846

though you'll have to add the finale on separately.

Thee is no reason not to do it with Table; the computation can be reduced to

tblBWV846 =
  Flatten[
    Table[
      ConstantArray[{bwv846[[i]], Take[bwv846[[i]], -3]}, 2], 
      {i, Length[bwv846]}]];

Beautiful music. Thanks for posting this question.

The code golf version

mainBWV846 = (ConstantArray[{#, #[[-3 ;;]]}, 2] & /@ bwv846) // Flatten;

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