I'd heard something in a TV documentary long ago, that 2nd violins used to be on the right - the documentary was discussing how Tchaikovsky's melodies would have been perceived to a contemporary audience & there was discussion of how building a melody from two independent lines, left- & right-panned would cause a 3rd, independent melody to become apparent to the audience; making a psycho-acoustic, but intentional, addition to what was written.
They demonstrated this using both a historical seating arrangement & also using simple synthesisers to generate similar psycho-acoustic lines.
It took me a while to try find any other reference - for some reason Google was not very forthcoming, but I eventually found this academic pdf, Orchestral Seating in Modern Performance: Origins & Variations, written as the MMus thesis by Jack Smith which would appear to back up that dim & distant recollection from the TV documentary.
It is one of the few constants in modern orchestral practice
that the first violins are seated to the left of the conductor. Almost
equally consistent is the seating of the second violins, who are now
most often found in a centre-left position behind the first; however
this practice was only introduced comparatively recently by Sir Henry
Wood (1869-1944) in the early twentieth century. This represents a
radical departure from the traditional seating, which placed the
second violins on the conductor’s right, opposite the first. Simple as
the differences may seem, the question of seating the violins is
easily the most controversial in any discussion of orchestral seating.
Whilst the arguments will be addressed in due course, it is should
here be pointed out that traditional practice was based on a principle
of balance: Arturo Toscanini (1867-1957) described the first and
second violins as being “like a pair of shoulders, and like shoulders
they must be strong and equal”. Arguably the perception of the second
violins as a subordinate and subsidiary section is a recent invention,
which may have arisen as an indirect result of the modern seating.
There is far more than just this simple paragraph, including diagrams of various seating arrangements used across history & different parts of the world.
Also, directly referring to the antiphonal structure available to that seating arrangement.
The Classical and Romantic repertoire abounds with antiphonal violin
writing, the effective portrayal of which is surely one of the
greatest benefits of traditional seating (but not, it will be
recalled, one of the original reasons for it). Although some
proponents of modern seating may dismiss these notions, one has to
wonder how selective they have been in studying the scores of such
works. Boult maintained that almost every piece in the main repertoire
contains moments of antiphony, with answering phrases from the second
violins becoming “a pale reflection instead of a vigorous rejoinder”
when they were placed in the modern position.
Further Googling would indicate that antiphony is not itself in the placing of the violins, but a way to separate the structures they are playing more effectively.
Dictionary definitions are along the lines of
1. the antiphonal singing of a musical composition by two choirs
2. any musical or other sound effect that answers or echoes another