I don't know why we can't just rotate them in the same role? It's a squad game now, and it's not like both players wouldn't benefit from regular rest, given their injury woes over recent years. When you add up all domestic, european and international games across a playing year, then I'm sure there's more than enough games to keep everyone happy (especially when they'll most likely still be on the bench and coming on as subs, even on their rest weeks).
Ditto for Ozil and Cazorla - if they both like playing the same role, then rotate them! Our other attacking options are now strong enough to handle it...