First of this is not a split file. The FICO score is for the credit file given to it . The credit file given to it is the you have the report for.
An example of a situation where a split file can occur is with a consumer whose fill name is Jonathon Doe JR. This consumer has applied for and received credit as Jonathon Doe and Jonathon Doe JR and Jon Doe JR and at two different addresses. The two fileswould be for the Jonathon Doe at address 1 and the second file for Jonathon Doe JR and Jon Doe JR at address 1 and 2. Most of the time this will not cause an issue. If the consumer updates the his address with his creditors you most likely will not see a problem. If there is credit the is unique to Jonathon Doe at address 1 then a you might have a problem. The bureuas may or may not consider Jonathon Doe or Jonathon Doe JR the same person depending other info in the conusmer credit file. Just becuase the SSN are the same it does not mean it is the person. The bureaus search criteria looks at Name, address , previous address, generation code, age, date of birth.
Here is a link you might find useful in understanding the score reasons.