Yes, but not at the same time.
While these disorders have virtually the same symptomatology, the duration they can be diagnosed is mutually exclusive. ASD can be diagnosed following a traumatic event from days 2-30, whereas PTSD can be diagnosed from day 30 onwards.
Part of the reason they’ve been separated is that there is a worry that by giving every stress-related disorder the label “PTSD,” we may be pathologizing normal, transient reactions in the days and weeks following a traumatic event that will go away on their own.