[Paul Maunder]

You can do this much more quickly than using bounce to disk. Just edit the two files together on the timeline and then rather than using the bounce to disk command, select the two adjacent regions and choose 'consolidate selection' from the edit menu (or press Shift+Option+3). This will then make a new single audio file from the original two and will appear on the timeline and in the audio regions list. Next go to the audio regions list, select the new full length audio file by clicking it and then choose 'Export selected as files' from the regions list menu at the top. You can then save this to disk in whatever format you choose. Alternatively, you could just use the newly consolidated file straight from your sessions audio files folder if it's already at the sample rate/bit depth you need it to be.