Hi uridiscence
In order to do this, you will need to edit the audio and
create a single clip that is timed to span the two slides. So for
starters, I'd examine the timing to determine exactly how long the
clip should be. Then edit the clip and copy/paste to create a clip
exactly that length. Then insert the clip on the first slide. You
should then see an option advising of a mismatch between audio
timing and slide timing. You will want to choose the bottom option.
Cheers... Rick