Apparently in the early to mid 19th century some pianos came equipped with una corda pedals that operated on only the treble notes, only on the bass notes, or both. Broadwood pianos had this feature; I was not able to find if other makers offered it.
Beethoven references this split una corda in the 4th Piano Concerto and at least one of his piano sonatas. The Wikipedia article on Piano Pedals says "Beethoven's Broadwood grand, presented as a gift to him from the Broadwood company in 1817, had an una corda pedal and a split damper pedal — one half was the damper for the treble strings, the other was for the bass strings." (Wikipedia "Piano Pedals" section "Beethoven and pedals", referencing Crombie, D. (1995). Piano: A Photographic History of the World's Most Celebrated Instrument, San Francisco: Miller Freeman Books, 19).
Hope this helps.