To move half to another sequence first split all tracks at the halfway point, using the SPLIT button.
Then select (highlight) all second-half tracks, audio and video. One way to do that is to hold down the <ctrl> key and click on each clip.
Then press the <ctrl-C> keys on the keyboard simultaneously. The will copy the clips.
Click the + sign to the right of the sequence 1 tab to add a blank sequence.
Press the <ctrl-V> keys on the keyboard simultaneously. That will paste the clips that you copied, though they may appear on different tracks.
If you make a mistake simply press <ctrl-Z> or EDIT|UNDO on the menu bar, to go back.
Now you can export each track independently.