I'm coming in a bit late on this conversation so I hope I am not repeating what has already been said, but botanical names can also have authorship at both specific and infraspecific levels, e.g. Centaurea apiculata Ledeb. ssp. adpressa (Ledeb.) Dostál

And to make it even more complex, you can have subspecies variants, so 2 infraspecific levels, e.g. Centaurea affinis Friv. ssp. affinis var. affinis

you are correct and it is relevant that such names are in use. However, the first is, according to the code redundant and not recommended. A name has only one authority.

The second is an expression of hierarchical arrangement, not a "name". It is similar to including expressions about subgenus grouping in a string like:

Rosa (Rosa) hemisphaerica

This means, it is not possible to have:

Centaurea affinis Friv. ssp. affinis var. affinis Centaurea affinis ssp. dissimilis var. affinis Breda

Gregor