For any one search id, there are many, sometimes hundreds, of log entries in introspection. Not all of these have CPU entries. Why are some missing? And what does each reading tell me? Since the last time, the CPU was in use X%? What does the normalized reading tell me?
There might be multiple entries of same SearchId (sid). But if you carefully look into the _raw events, you could see the "process ID" (pid) and parentProcess ID would be different. (or the component might be different)