The Two-Headed Alien is one of the characters in Putt-Putt Goes to the Moon. One is male and one is female. They each speak one line and a half.
The two-headed alien act as the only owner/employee of the rocket ice cream stand. After Rover and the alien reveal to Putt-Putt that the stand is for sale and can be used to return to Earth, they also reveal the rocket is missing a few parts. They allow Putt-Putt to take the diagram flag from their stand as it will tell him what he needs to finish the rocket.
After Putt-Putt buys the rocket ship with ten Glowing Moon Crystals, they will leave the rocket ice cream stand and take everything that made it an ice cream stand with them, making the inside of the rocket accessible to Putt-Putt and Rover.