I've seen house rules that address this, and, since most of my players have played together since 1e, and we like consistency in the experiences of our characters' worlds, we've tried to accomodate it. Li Shenron's points about having the same prerequisites and paying the same costs is roughly what we do (different DMs, different choices).
If you're concerned about official rules, then no, you can't do it. If you're interested in optional ways of handling magic then it's all about house rules.
Dave