This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
Just a wild guess.. The JVM takes all the .class files it finds in the directories specified by the classpath and stores them using the package and class name in a list. When you specify the class to execute, the JVM does not associate that class name with a specific file, but with the real class stored in memory?
Just thinking here.. No facts! Just what I would handle it as a JVM programmer ;-)