Multi-Vehicle(zephyr and iris) ardupilot gazebo simulation: Going to different points in Gazebo simulation for the same 'lat lon alt'

Hello community members

I want to simulate a zephyr fixed-wing and an iris copter in one gazebo simulation using SwiftGust/ardupilot_gazebo repository.
So What I have done is, I have opened the zephyr demo world in gazebo and inserted an iris model into the environment and finally saved that file as another file. after that I run SITL simulation for both iris and zephyr in the same location through -L option in command. So I can assume when I give a guided lat lon alt command with the same arguments to both drones, the drones move toward a same location in the gazebo simulation, but each of them goes to a different place.
I have tried to set the same yaw values for drones in gazebo, but it does not help and simulation result was the same behavior. Also I have read somethings about WGS84 but I don’t think it is important in my problem because it is the location of the world origin and the other things would have relative locations.