!($1 in seen) { seen[$1] = 1; order[++n] = $1 }
{ value[$1, $2] = $3 }
END {
  print "sample", "before", "after"
  for (i = 1; i <= n; i++) {
    id = order[i]; print id, value[id, "before"], value[id, "after"]
  }
}