  The conductance through a serial double dot structure for which the inter-dot
tunneling is stronger than the tunneling to the leads is studied using the
numerical density matrix renormalization group method and analytic arguments.
When the dots are occupied by 1 or 3 electrons the usual Kondo peak is
obtained. For the case in which 2 electrons occupy the molecule a singlet is
formed. Nevertheless, the conductance in that case has a constant non-zero
value, and might even be equal to the maximum conductance of $2 e^2/h$ for
certain values of the molecule parameters. We show that this is the result of
the subtle interplay between the symmetric and anti-symmetric orbitals of the
molecule caused by interactions and interference.
