  We propose that a pertinently engineered double superconducting island
connected to two spinless one-dimensional conducting leads can work as a
tunable (iso)spin Kondo and charge Kondo system, with the lead index regarded
as an effective isospin degree of freedom. We evidence how, by tuning a single
gate voltage applied to the island, it is possible to make the system switch
from the (iso)spin Kondo to the charge-Kondo phase, passing across an
intermediate phase, in which the Kondo impurity is effectively irrelevant for
the low-temperature behavior of the system.
  Eventually, we evidence how to probe the various phases by measuring the ac
conductance tensor of our system, by emphasizing the features that should allow
to identify the onset of the so far quite elusive "charge-2" charge-Kondo
effect.
