A suitable name for a large planet with a similar atmosphere to Earth's, but twice as big and twice as heavy, could be "Gaia Prime." This name combines the concept of "Gaia," which refers to the Earth as a living, interconnected system, with the term "Prime" to signify its larger size and enhanced qualities. "Gaia Prime" evokes the idea of a planet that embodies Earth-like characteristics but on a grander scale.