Near-boundary flight is commonplace for multirotor vehicles today. Boundary effects such as the ground and ceiling effect, which provide increased thrust and decreased power consumption, are vital for the future of efficient flight as they are important for performance and safety. In this paper, the impact of rotor--rotor interactions with varying rotor hub distances on each rotor's near-boundary performance (thrust and power) was investigated. The results show that as the rotors decrease in separation distance from each other, the near-boundary effects increase, providing performance benefits for the vehicle. However, the opposite happens as the rotor hub distances increase; the performance near the ground degrades. The current results can be used for future understanding of multirotor interactions near boundaries, leading to better vehicle design and potentially getting increased performance benefits in near-boundary flight for multirotor vehicles.