I recently responded to a question from a student about signing up to multiple distributors like CD Baby and Tunecore. It was a great question so I thought I would post my response here for those who may have the same question.
There are advantages and disadvantages of signing up with multiple distributors and it is up to you as to which approach would be better for your situation.
The advantages of having multiple distributors is that if one goes down (like CD Baby did last week) you have other options. You also have the advantage of getting coverage in one channel that might not be covered by another. The disadvantage, however, is that you have multiple versions with multiple ISRC codes of the same song or album showing up on places like Amazon and iTunes. If you are trying to get ranked on Soundscan for the Billboard chart it will definitely not be a good idea.
You have to make the call as to what’s more important to you. Personally, I find it easier to work with just one (most of my stuff is on CD Baby) but when I first started using distributors I signed up to a couple because no one dominated the scene yet. I am grandfathered in on Orchard (who used to be IUMA).