Plenty of people can do both or can change from one to another. But it still seems to be that the interview focus should be different as both positions require somewhat different focus.
I don't mind interview having also part where code is written at all. Be it dummy feature or breadth/depth first search or fizzbuzz or any other simple reasonably sized assignment. But in case of senior as in partly decision maker with not much direct supervision in the long term, you need those other capabilities too.