I've had this thought too.
I've been a student of a number of different professors (~4) in our philosophy department, and was wondering whether or not I could have multiple people sign one letter as a sort of quasi-committee evaluation; it's a small department, with small class sizes, so I have significant relationships with each. Surely, having multiple people vouch for you couldn't be a bad thing... but I don't know. I don't know if that would just be "weird" to the adcomms, or what. Care to comment,
@LizzyM @Goro et al.?