
Sean,
If you are looking at actual effort, then you will be running your report looking at timesheet data. You can know who reported time using the reported by field and again the time will be booked against a task (eat lunch in your example) if you also bring in the 'parent project' for the task then you will be able to differentiate between which project each person has booked against.
If you are using the actual effort field from the task data, then the parent project field would work there also.
Hope that helps, we have exactly the same situation, where our standard template is full of tasks that are now appearing dozens of times across the portfolio.
Phil