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