I wanted to update this just in case anyone stumbles across it in the future. I ended up not doing a second pitch before bottling despite the recipe in Beer Captured (they pretty much all recommend a second pitch) and the bottles carbonated just fine.
In summary -- (2) Belgian strong ales, both dark, OGs of 1.078 and 1.058, fermented six weeks with Wyeast 1388. Bottled conditioned for six weeks, carbonation was right on, beers tasted delicious. Assume the authors were given free yeast to reccomend second pitches.