\version "2.23.3"

#(define (double-bar-number increase-amount)
  (lambda (barnum measure-pos alt-number context)
    #{
      \markup {
        \line {
          #(robust-bar-number-function barnum measure-pos alt-number context)
          \concat { (
            #(robust-bar-number-function
             (+ increase-amount barnum) measure-pos alt-number context) )
          }
        }
      }
    #}
  )
)

musica = \relative c'' {
  \override MultiMeasureRest.expand-limit = #3
  \compressEmptyMeasures
  | R1*7
  | r4 b a g
  
  \set Score.barNumberFormatter = #(double-bar-number 4)
  \repeat volta 2 {
    | fis1~
    | fis4 b a g
    \break
    
    | fis1~
  }
  \alternative {
    { | fis4 b a g }
    { | b8 b a a g g fis fis }
  }
  \set Score.barNumberFormatter = #robust-bar-number-function
  \set Score.currentBarNumber = #17
  
  | b b a a g g fis fis
}

\score {
  \new Staff \musica
  \layout{
    \override Score.SystemStartBar.collapse-height = #1
    \override Score.BarNumber.break-visibility = #end-of-line-invisible
    \override Score.BarNumber.direction = #DOWN
  }
}