Having two test classes that extend an abstract class that provides the deployment archive (actually the fact that they extend an abstract class is insignificant, the important point here is that the deployment archive name is the same).
When the test classes run individually pass the test. When these two test classes combined in a test suite, the first only pass and the second always fails.

@RunWith(Suite.class)
@SuiteClasses({
RegisteredEchoServletTestCase.class,
RegisteredEchoServletTestCase2.class
})
public class MyTestSuite {

}

Find attached @RunWith(Suite.class)
@SuiteClasses({
RegisteredEchoServletTestCase.class,
RegisteredEchoServletTestCase2.class
})
public class MyTestSuite {

}

Issue exists only on tomcat 6 container. I run the same test suite against tomcat-embedded-7 with success.

George