69 Camaro tailight issues.

[Chevrolaine]

My brothers Camaro has always had issues with the tailights. Being that the harness was quite old and original with a few splices from unknown origins he replaced it with a new one and still has the same problem.

Basically the inner lights are brighter than the outer in such that it looks like the brake lights are always on. When you hit the brakes, the outer ones come on to match the brightness of the inner lights.

I believe the inner ones are to be tailights only correct??

Ideas, suggestions?? Were stumped.