Its really not useful for me to speculate about such specifics - presumably your own psychiatrist ( GPs shouldnt be deciding the treatment of Bipolar Disorder or using such drugs )had good reasons for selecting this particular combination for you ? He certainly had a duty to explain it to you fully, and to check that you understood this. Only he can explain his reasons for selecting this particular combination. Valdoxane is a very interesting new drug, and some medical aids or options might not yet approve ofm it for routine use, but your doc would need to communicate with the medical aid to persuade them to cover this, if he felt it had special advantages for you - it is chemically and in other ways significantly different from the other ADs in common usage, and rather too newly released for their to be a generic version available yet. Any generic is supposed by law and regulation to have good evidence of being biologically fully equivalent to the more expensive original version of a drug.
But these are valid concerns for you to discuss with your prescribing doc, who knows the details of your case and his reasonaing for this recommendation