The last few weekends have seen moviegoers pouring back into theaters thanks to the head-to-head blockbusters Barbie and Oppenheimer. Their dual openings made for one of the highest-grossing non-holiday weekends ever, and the talents of Greta Gerwig (co-writer/director of the zingy comedy based on the popular doll) and Christopher Nolan (writer/director of the epic biopic about the man who spearheaded America's creation of the atomic bomb) have already netted a cumulative $1 billion at the box