A lower-mobility parallel manipulator with multiple operation modes can be considered as inherently reconfigurable. This is the case for 4-RUU parallel manipulators that have three different operation modes. Allowing the first revolute joint axis to have any horizontal orientation leads to a dual reconfigurable 4-rRUU mechanism. This paper presents an interpolation approach to determine its operation modes as functions of the orientation of its base revolute joint axes. Furthermore, its limb singularities are characterized by differentiating the constraint equations with respect to the actuated joint variables which are further used to visualize its translational workspace for three mutually perpendicular orientations of its base revolute joint axes.