I have been asked these 2 questions by some of my users:
1. what happens when a timesheet (MSPS 2007, SP2), is imported twice into the “My Tasks” page.
2. Can a Timesheet import to My tasks be done out of sequence?

For Item 1, Project Server ignores the update the second time. So the hours imported would not change. However, if you changed your actual start/finish dates from what is reported in the timesheet, this is reset to what is in Timesheet.

For Item 2, again, importing Timesheets out of sequence would not impact anything. It will just roll up into the total actuals, the way it should.

However in both cases the thing to remember is that, if any “actual” data has been modified on “My Tasks” page, this will get reset to what was reported in “Timesheet” data.