The Includes folder of model document revisions contains all documents that are included in this revision. Note that it does not refer to revisions, because an ITP include statement inside a model document does not refer explicitly to a particular revision. Whenever this revision of the model gets compiled, it will include the revision of the indicated document that is [current] or [in development] at that moment.
So the ITP/MDK Repository does not guarantee that a recompile of a particular source revision always results in exactly the same model. It does however store all model revisions that have ever been created, so instead of recompiling a particular model one can simply retrieve it.