exclusion of transitive dependency is too dominant

Please consider the following structure: I've got a module M that has got the dependencies D1 and D2. Both D1 and D2 depend on a transitive dependency T.

I have excluded T from D1 per <exclusion> on the M POM in the dependency to D1.

Now, one would expect that T is still pulled into M, because there is no exclusion on the D2 path. But this is not the case, "mvn site" on M is missing T (in the dependency report), and it is missing from the classpath, too. However "mvn eclipse:eclipse" on M does the job right: T is listed.