If a user creates a Maven Archetype-based project example using the default example name (ex: jboss-javaee6-webapp6), then he can not create a 2nd example under a different name. A dialog box pops up and asks to overwrite (i.e delete) the existing jboss-javaee6-webapp6 project.
If the user answers yes, he loses his existing project, if he answers no, the project creation halts.

For archetype based projects, where the generated project name can be set by the user, the ImportMavenArchetypeProjectExample should not prevent the user from creating several projects based on the same example. The maven archetype wizard page has a built-in check that will prevent duplicate projects.

IMHO deleting project examples where the project name is variable doesn't make sense (as opposed to regular examples where the name cannot be changed)