\new Voice copies inserted staff two times

[Bernadette]

I need to create a Voice environment, because I want to use the balloon
engraver to annotate chords inside the staff.
I need only one staff, but get the staff engraved correctly once, and then
two times one octave lower.

Code-snippet:

 \new Voice \with {\consists "Balloon_engraver"}{
        <c-\balloonText#'(1 . -1) \markup {\tiny "Grundton" } 
f-\balloonText#'(3 .
0) \markup {\tiny "r. Quarte" } g-\balloonText#'(2.5 . 1) \markup {\tiny "r.
Quinte" }>1_\markup{Quartakkorde}
        <c-\balloonText#'(1 . -1) \markup {\tiny "Grundton" }
d-\balloonText#'(3 . 0) \markup {\tiny "gr. Sekunde" } g-\balloonText#'(2.5
. 1) \markup {\tiny "r. Quinte" }>
        <c-\balloonText#'(1 . -1) \markup {\tiny "Grundton" }
f-\balloonText#'(3 . 0) \markup {\tiny "r. Quarte" } bes-\balloonText#'(2.5
. 1) \markup {\tiny "kl. Septime" }>
        }