  I study the possible phase transitions when two layers at filling factor
$\nu_t=1$ are gradually separated. In the bosonic case the system should
undergo a pairing transition from a Fermi liquid to an incompressible state. In
the Fermionic case, the state evolves from an incompressible $(1,1,1)$ state to
a Fermi liquid. I speculate that there is an intermediate phase involving
charge two quasiparticles.
