There are definitely advantages of cell phone cloning. For example, if your phone fell in the toilet and you needed an exact replica to convince your parents of responsibility, it would be the perfect disguise.
Instant communication / Instant interruption Constant production / Constant distraction Higher productivity for people who use the phone for business / Lower productivity for people who take time...
A few of the advantages are being able to upgrade easier and cheaper, also getting a lower rate and just being able to upgrade to new and better plans.