Possible Clues:

• Two lives on river
• Si Si - she's an Egyption goddess
• Goddess of detached territories?
• A name for the Thames at Oxford and upstream
• Osiris' spouse
• Egyptian goddess - the Thames at Oxford
• Are, perhaps, a single deity
• "It depends on what the definition of ___"
• The god that has a double existence?
• Are, perhaps, one goddess from Egypt - or from Oxford