Two packages, different routes?

I was sent 2 packages from Italy, same size, same weight, picked up by Fedex same day and time. One was sent to Belgium and then arrived in the US in time, the other was sent to France (CDX) and has been stuck there for 2 weeks, apparently in customs (there are delays according to customer service). Has this ever happened to anybody else? What is the rationale behind splitting the two packages in transit?