If the sequence number is same for 2 approvers then it does not mean that one of them can approve the timesheet.  They being in the same sequence will still have to approve the timesheets, however they will receive the timesheet at the same time.
 
For example: If you create an approval path called Project Leader > Supervisor and set the sequence as 1 for both of them then the project leader as well as the Supervisor will receive the timesheet for approval at the same time. However both of them need to approve the timesheet.