  The double burst, GRB 110709B, triggered Swift/BAT twice at 21:32:39 UT and
21:43:45 UT, respectively, on 9 July 2011. This is the first time we observed a
GRB with two BAT triggers. In this paper, we present simultaneous Swift and
Konus-WIND observations of this unusual GRB and its afterglow. If the two
events originated from the same physical progenitor, their different
time-dependent spectral evolution suggests they must belong to different
episodes of the central engine, which may be a magnetar-to-BH accretion system.
