stackin engine upgrades of the same type on the muscle car has no effect BUG?

[Don Quixote]

stacked 2 compressors on the muscle car, hoping that when i lose a durability point BOTH would activate, removing 2 threats. but it seems like only one is activating? if this is intended functionality it would probably help to just not allow 2 engine upgrades of the same type to be equipped at once, though would be cool if it just worked

[malogoss]

I would assume it's not a bug, but it's not well explained in the game either. I personally went for 2x the brakes that delete a threat after skipping a turn, I was kind of disappointed it did not do what I was expecting, but oh well, it's fine.