It sometimes appears that faulting is more complex than just a single fault plane breaking with a single sense of motion. So, for example, the Denali earthquake in 2002 started on a thrust fault, then jumped to a nearby strike-slip fault for most of the rupture. I'd call it all the same earthquake, just changing mechanics as the break progressed.

Dual asperities - it is true that sometimes fault breakage can take the form of slip, then a pause, then more slip. Also, sometimes one fault patch breaks, then another separated by some distance slips next. In extreme cases, it is not clear what to call a foreshock, a mainshock, and the aftershocks, but these are really just definitions.

I've seen no indication that yesterday's earthquake had much spatial or temporal complexity in the rupture, although really I haven't seen the results of any serious analysis.