I’ll be honest, I don’t think those really have much of a history. There’s probably some obscure case I’m simply not aware of, but the only thing I can think of is Darth Maul. My recollection is; Ray Park was just using a staff form.
I’ve got a double knife around here, somewhere. I picked it up as a show piece item about a decade ago. But, I’ve never even seen a double knife presented as a practical weapon.
Okay, on the ability to actually use them? Maul’s lightsaber works because they’re effectively frictionless, and the individual blades can be turned off. If you take away either of those, I’d really worry about being able to control weapon, when actually connecting with another combatant or their weapon.
With staff combat, the closer your hands are, the faster you can move, but the less control you have over the weapon, which in turn means you have to slow down (yes, by staff standards, Maul was moving slowly). I don’t think this is really even a skill issue, simply controlling a double bladed sword would always be finicky.
I would believe that double weapons were used as exhibition pieces, but as combat weapons, without more information, I’m pretty suspicious.
Double knives are slightly more plausible. I’m not aware of any history, and, my own experience left me with a nasty self inflicted cut on my off hand, but there are enough uses for a reverse grip blade that having one there all the time wouldn’t be a complete liability. But, carrying one could be. Mine uses a lockblade mechanism, but in a setting without collapsible knives, I’m not sure how you’d keep yourself safe from your own blades.