  We present new results related to the coupled evolution of a two giant planet
system embedded in a protoplanetary disk, in which a Saturn mass protoplanet is
trapped in an outer mean motion resonance with a Jupiter mass protoplanet. The
gaps opened in the disk by the two planets overlap, therefore the two planet
system exchanges angular momentum with the disk at the inner planet's Inner
Lindblad Resonances (ILRs) and at the outer planet Outer Lindblad Resonances
(OLRs). Since the torques are proportional to the square of the planet masses,
and since the inner planet is about three times more massive than the outer
one, the ILR torques are favored by a factor ~10 with respect to the one planet
case. In the case presented here, this leads to a positive differential
Lindblad torque and consequently an outwards migration. We briefly discuss the
long-term behavior of the system, which could account for the high
eccentricities of the extra-solar planets with semi-major axis a>0.2 AU.
