AB40k Maintainers

I was reading the Force Organizational info on page 81. Where it talks about being able to field 2 HQs per HQ slot it also mentions not being able to use 2 characters with the same saga. Is this purely for fluff, or can I really not use Logan Grimnar and Njal Stormcaller together?

Page 64, 2nd paragraph - "The exception to this rule is Special Characters..." in the context of stating that no two chracters may have the same Saga in the sentence before the above excerpt.

ty sir