It didn't split into 4 in one event. It first split into two then a few months later one of those split an so on.
What was unusual was that it arrived (probably 15 years ago now) with two mouths and remained that way for several years (never got photo). On its first split, which took at least a month, one mouth ended up in each 1/2. With the later splits it did it in the usual time-frame of a day or so.