Transport properties through a two-level quantum dot are studied using the Anderson Hamiltonian. Like the spin degeneracy, the orbital degrees of freedom in the quantum dot cause the Kondo effect and dephasing of conduction electrons transported through the dot. One feature of the model is the mixing of orbital states in the dot which occurs even if the Coulomb interaction is absent. This mixing deforms the density of states in the dot and suppresses the increment of the current caused by the Kondo effect. The dephasing processes are enhanced when the bias voltage is increased, but are insensitive to the mixing effect.