  The recent experiment by Y. Shin \emph{et al.} [Phys. Rev. Lett. \textbf{93},
160406 (2004)] on the decay of a doubly quantized vortex imprinted in $^{23}%
$Na condensates is analyzed by numerically solving the Gross-Pitaevskii
equation. Our results, which are in very good quantitative agreement with the
experiment, demonstrate that the vortex decay is mainly a consequence of
dynamical instability. Despite apparent contradictions, the local density
approach is consistent with the experimental results. The monotonic increase
observed in the vortex lifetimes is a consequence of the fact that, for large
condensates, the measured lifetimes incorporate the time it takes for the
initial perturbation to reach the central slice. When considered locally, the
splitting occurs approximately at the same time in every condensate, regardless
of its size.
