Thanks for the replies.  I guess built into my question was whether redundant personal anchors are necessary when sport climbing. 
  
Personally, I used to use two shoulder length slings (on separate bolts), but found they were too short to be comfortable, so I would end up girth hitching them together in some cases to make a longer one, but the length would be too much sometimes. 
  
Now I use a loop chain girth hitched to my belay loop with a locking 'biner on one of the anchor bolts (or a third bolt, if present).  I found this is much easier for adjusting the length, but without the cross-clipping danger of a daisy chain.  I only have one, so I was wondering if people thought that was enough, or if I should back it up either with the rope (when continuing up) or with another sling (when rappelling).