Groups of Animal Rebellion supporters with banners calling for a switch to ‘plant-based food system” stopped and climbed onto company trucks outside the factory on September 4 last year.
Thames Valley Police said 23 people had been arrested.
Ditton, of Silver Road, and Barnes, of Old Library Mews, are both charged with obstructing or disrupting lawful activity.
At the time, Animal Rebellion, who accused the companies of not ‘tackling the climate crisis’, said its activists had also let down the tyres of trucks, filled pipes with expanding foam, climbed milk silos and entered the sites’ loading bays.