two are no more trouble/cost than one. I've only ever had two and they have always been really bonded and I feel better knowing they have each other to entertain and share fears with each other. During the 89 quake here in SF, I finally walked home (about 10 miles) and found both my boys under the kitchen table (amid much rubble) hugging each other. Broke my heart but I can't imagine what would have happened if there was one.
Claudia