Late last year I made Northern Brewer's Belgian Dubbel extract kit and it was fantastic. People liked it so much that they asked me to make another batch and sell them some. Which I did, but they said it was "meh". My buddy made the same thing and I sampled it tonight. Compared to my first batch I have to agree it was meh. Unfortunately I lack the palate and vocabulary to properly describe the differences in taste, but I did recently remember that there was a difference between my first attempt and the subsequent ones. The first time I brewed it I used a Wyeast smack pack, which I smacked and set aside the morning I brewed. The pouch barely got puffy over a period of several hours. I realized I was missing a grain sack before I got started so I went to my LHBS to get one and bought a vial of White Labs yeast just to be safe (they were out of Wyeast). I used both yeasts.
So my question is, for a high gravity ale does can it hurt to use double the yeast? Assuming that the original Wyeast pack was partially viable, should I make the next batch with 1.5 times the yeast?