  We analyse a blow-up sequence of solutions for Liouville type equations
involving Dirac measures with "collapsing" poles. We consider the case where
blow-up occurs exactly at a point where the poles coalesce.
  After proving that a "quantization" property still holds for the "blow-up
mass", we obtain precise point-wise estimates when blow-up occurs with the
least blow-up mass.
  Interestingly, such estimates express the exact analogue of those obtained
for "bubble" solutions of "regular" Liouville equations, when the "collapsing"
Dirac measures are neglected. Such information will be used to describe the
asymptotic behaviour of minimizers of the Donaldson functional introduced by
Goncalves and Uhlenbeck (2007), yielding to mean curvature 1-immersions of
surfaces into hyperbolic 3-manifolds.
