Back in the late 1970s I worked for a while in the camera department for Sears Canada. As I recall it, we sold some Hanimex flashes - but they were very unreliable!

I wouldn't be surprised if many of the companies who were into re-branding were focussed mainly on price points and feature lists. That way, they could sell to retailers like Sears, who liked to offer lower priced options.

While at Sears we weren't restricted to off-brand items - we sold tremendous volumes of Canon AE1s and Canon A1s, as well as TXs and AT1s, IIRC. We were also one of the few stores that sold Olympus, but only the OM10. If you wanted an interesting lens, however, we would have to special order it for you.

I still have a store demonstrator Zuiko 75-150mm f/4.0 lens I bought from work for a silly low price before I left there in 1980 .