I have a jar file - it happens to be generated from an XML schema using JAXB.

I have just noticed that in the same path inside that jar, I have 2 classes with the exact same name. As a matter of fact, if I unzip the jar using 7-zip, Windows asks me whether I want to replace file "blah.class" with "blah.class".

How can this be possible? Both from a Java perspective and from a filesystem perspective? Does the zip format allow for this? I tried to google around but to no avail.

Thanks,
David.