template parameter redeclaration

This is what I want to achieve. The leaf component will inherit Component<ParentT>, others will inherit Component<ParentT, ChildT>

template <typename T>
class Component{
  protected:
    typedef Component<T> ParentComponentT;
  ...
};

template <typename ParentT, typename ChildT>
class Component: public Component<ParentT>{
  protected:
    typedef std::vector<ChildT*> CollectionT;
  ...
};

But the problem is Template parameters getting redeclared. and I cannot move the second one above first one because second one inherits first one.

error: redeclared with 2 template parameter(s)
note: previous declaration ‘template class Component’ used 1 template parameter(s)