System Information
Operating system: Linux-4.4.0-151-generic-x86_64-with-debian-stretch-sid 64 Bits
Graphics card: GeForce GTX 1080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 430.26

Blender Version
Broken: version: 2.81 (sub 1), branch: master, commit date: 2019-08-04 08:21, hash: rBdd3cdf6f1e9d
Worked: (optional)

Short description of error
Camera Background images apparently are a selectable element, at least in wireframe view.

Exact steps for others to reproduce the error
Open this file:

Try to select the small Cube which is inside the G7 square of the UV background image. When I click there, it first selects the camera, only after the second click it selects the cube.
Now turn Background Images off, select the bigger cube in the center again and try again to select the small cube in G7. It will select the cube on the first click.

This bug plays a role in a somewhat related problem, which I am going to report separately. (This one: T68221)
In any case, I doubt this is the intended behavior, at least it should not be.