If that was the intention, it failed Two parallel small tubes in a parallel orientation are in no direction stiffer than a single, larger tube of the same weight.

Go to your local hardware store, pick a plastic tube of large diameter, hold it on both ends and try to twist that. Repeat same with two smaller tubes of same material and combined weight, held in parallel to each other...
When used on bikes, it will combine a less stabile BB with additional weight

This dual tube thingie (Colnago did the same with early Ti and CF frames) is a workaround typically used when no pre-made tube of the desired large diameter is to be had. Of course, the shortcomings of such a design are usually described in marketing brochures as "adding comfort" and such things.

On a classic, this is no issue because such little oddities just add charm