The emulator cannot control the 2:1 ratio of FPS:VPS. It is determined entirely by the game.
However, Dolphin can tell the game that it is running on an interlaced TV or progressive scan TV. Interlaced TV's are 2:1 ratio and progressive TV's are 1:1. The Accurate VBeam emulation tries to detect the sort of TV that the game is requesting and emulates the 2:1 or 1:1 ratio. The emulation still needs more work which is why it is an option right now.
However, Dolphin can tell the game that it is running on an interlaced TV or progressive scan TV. Interlaced TV's are 2:1 ratio and progressive TV's are 1:1. The Accurate VBeam emulation tries to detect the sort of TV that the game is requesting and emulates the 2:1 or 1:1 ratio. The emulation still needs more work which is why it is an option right now.