How odd. I tested using
Servlet 2.3, JSP 1.2, JDK 1.4.2, and
Struts 1.1 I believe. I don't remember the exact version of
Tomcat I was using. Just out of curiousity, did you run the exact code I posted above? Not that I'm doubting you, I just find it interesting.
I guess the other thing you might be able to do is determine in your Action which bean to put in scope, that way you always have the right bean available for your JSP without having to do the conditionals there.