Why do people have back-up horns? I'm not the most experienced player, so I've never felt the need to get a second of the same type of horn. I was wondering why a person would get 2 Tenors or Altos or what have you. (I'm not talking collectors, however, that's a different animal.) When do you use your backup? How did you convince your wife you NEEDED 2 of the exact same multi-thousand dollar thing?