By default when a session is recorded, the session details will show the whole session rather than the time between the two halves. However, this can be changed so it only shows data within the two halves.
Here is an example of a session that lasted 30 minutes, but the two halves were set for 10 minutes each:
To show match data only we need to edit the session and select 'Match Data Only':
Once this is selected and we then check session details once more, the session only shows the time between the two halves: