Two different stars simultaneously rose and simultaneously went over the horizon. Where is the observer on Earth?

For any latitude of the Earth (except for the poles, where stars do not rise or set), two different stars, simultaneously rising at different (even close) points of the horizon, have different declination. At any latitude other than the equator, this will mean a different period of time from sunrise to sunset. And only at the equator do all the stars set exactly 12 hours after sunrise (if refraction is not taken into account). Therefore, the observer is at the equator.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.