An isolated parallel-plate capacitor with capacitance \(C_0\) is charged to a potential difference \(V_0\), storing total electric charge \(Q_0\) and electric potential energy \(U_0\). The capacitor is disconnected from the charging source and then connected in parallel to an uncharged capacitor of capacitance \(2C_0\). After electrostatic equilibrium is established, what are the final charge \(Q_2\) stored on the capacitor of capacitance \(2C_0\) and the final total electric potential energy \(U_{\text{final}}\) stored in the two-capacitor system?