Automaton Weapon Effect does not apply to both weapons when dual wielding

Just wondering if this was intentional or if its a bug? I had just purchased the weapon effect and I'd quite like it to appear on both my weapons while I'm dual wielding. Literally every other weapon effect I own does this by default.

Only supporter pack weapon effects cover both weapons because the packs only give one mtx.

Any weapon effect purchased through the mtx shop only affects one weapon. Always been like this.

You'll need to buy a second copy of the effect to get it on your other weapon.