In theory there is nothing wrong with starting 3 or possibly more players on any givin weeks line-up. The obvious example being that if you owned P. Manning, J. Addai, R.Wayne, and D.Clark, you would more than likely start all of them every week and probably end up successful on most weeks. Of course the chances of anybody actually having all four INDY players is highly unlikely unless you are playing in a 4-team Yahoo league against your girlfriend, your grand-mother, and your pilate instructer.
But look at a far more realistic example.
WK 2
CLE QB D.Anderson 328 yds, 5 TD
CLE RB J.Lewis 216 yds, 1 TD
CLE WR B.Edwards 146 yds, 2 TD
CLE TE K.Winslow Jr. 100 yds, 1 TD
Those are numbers any fantasy owner would love to see at those 4 positions. How many would actually have all 4, let alone have the stones, stupidity, or amazing foresight to actually start them is irrelevant. There can be no denying that a roster like that could concievably exist. Not thru trades or keepers, but thru the draft.
It is important to point out, and I'm sure I don't need to, that the above example was a complete fluke. The Cleveland FREAKIN Browns. An unexplainable NFL oddity. The chances that those four players, could have stats like that all in the same game are about as unlikely as Travis Henry winning "Father of the Year".
Personally, and I am no expert, would not feel comfortable doing it. Too much to risk 3 or 4 starting spots all on the play of they're respective QB. Even with the pipe-dream Indy 4 that I mentioned above, I wouldn't like it. Peyton gets hurt, gets pulled for whatever reason, or God forbid just have a bad game, and I would be screwed. On seperate teams, or in pairs they are all must starts. Representing almost half of my starting line-up, never happen.