The sudden spin-down in the rotation of magnetar 1E 2259+586 observed by Archibald et al.
(2013) was a rare event. However this particular event, referred to as an anti-glitch, was followed
by another event which Archibald et al. (2013) suggested could either be a conventional glitch or
another anti-glitch. Although there is no accompanied radiation activity or pulse profile change, there
is decisive evidence for the existence of the second timing event, judging from the timing data. We
apply Bayesian Model Selection to quantitatively determine which of these possibilities better explains
the observed data. We show that the observed data strongly supports the presence of two successive
anti-glitches with a Bayes Factor, often called the odds ratio, greater than 40. Furthermore, we show
that the second anti-glitch has an associated frequency change Δν of -8.2 X 10<sup>8</sup> Hz. We discuss the
implications of these results for possible physical mechanisms behind this anti-glitch
