I'm experiencing exactly this (old) bug:
http://bugs.modx.com/issues/2819
on a MODX Revolution 2.1.3-pl (traditional) installation...
Setting a default template for a new resource with a certain parent works for the first rule, not for the following. The new template is set, but the form fields and FC rules that go with it are not displayed. Instead, the FC rules for the parent template are applied. If I deactivate the first rule, the second one is working, the rest still has no effect.
Anyone else got this problem / is it a bug?