Flux Overdrive bonus stacks additively with other status mods equipped, similar to how dual stat mods work.
While the mod is generally useless as increasing the status chance with dual stat mods already equipped offers minimal bonuses, it does work well when modding with two or less elemental mods, where the player wants to maximize the chance for slash or a specific elemental proc without adding other elementals that take away from the chance of their preferred elementals from proccing.
As an example, modding for corrosive damage with two dual stat mods and adding Primed Bane of Grineer with this mod will give the weapon over 90% status chance, enough to proc one status a second. Due to the weapon only having corrosive damage, the slash procs will occur often and due to the bane mod, they will be more damaging. This build allows for the weapon to function better against heavy armor due to slash procs ignoring said armor.