The Duplicant is the upgraded version of the Clairvoyant when one is infused by a Nanofiber Sync. It is a completely different entity that no longer resembles its former self in any way, shape or form, and uses weaponized nanites that allows it to "infiltrate" enemy infantry and multiplies itself through a rather gruesome procedure.
The Duplicant's body are also capable of repairing itself in an alarming rate, making these drones a frightening sight to behold by infantry, especially when massed in hordes.
The nanofibers turn Clairvoyants into little bug-like objects, who instead of infiltrating enemy structures will begin to infiltrate human bodies. The moment its Nanofiber Sync happens, the nanomachines inside the Clairvoyant's body start rapidly multiplying. This continuous process results in them requiring much more additional resources in order to last and spread.
This is why they form this weird body, the Duplicant, which will crawl towards enemy infantry in order to 'devour' them and use the collected materials for more multiplying. Keep in mind, that once a Duplicant performs its attack, it will temporarily disassemble so that it can take over another body, but if it fails to do so, the nanites will not be able to reassemble back into a Duplicant body. One Duplicant can devour more than just one enemy soldier, so if it attacks accurately, a massive chain reaction might take place.
The structure of a Duplicant is very different compared to that of the Clairvoyant's, as it is a body the nanomachines of which are only driven by the goal to multiply. Since its small tools and the windspin drive get consumed by the reprogrammed nanites, the Duplicant can neither cross water areas, or gain speed boosts near the Spinblades. However, thanks to the continuous multiplying of the nanites in its body, it becomes sturdier, and can regenerate from the damage taken relatively well.
The Duplicant is a special kind of scout infantry available to the Foehn Revolt via the Nanofiber Sync ability. It has only one role: rush groups of enemy infantry and transform them into Duplicants. They can be used to quickly clear out large crowds of infantry units (as the Revolt lacks suitable weapons that specialize in clearing out large crowds of infantry in the early and midgame), attack vital infantry units such as Engineers, or act as an unconventional counter against expensive yet fragile infantry units such as Chrono Legionnaires. They are particularly useful against the Epsilon as a whole, as their faction mainly relies on infantry units but many of them lack durability, not to mention the Duplicant is immune to their more exotic weapons (namely, mind control and poison).
It should be noted that if you want to command a large number of Duplicants to attack enemy infantry, you must not let them all aim at single target, as they may all detonate at that one victim at once and potentially let them go to waste. In addition, Duplicants must avoid anti-infantry vehicles and defense structures as they cannot do anything against them. However, the Duplicators can attack Soviet Desolators and Eradicators safely as they are immune to radiation beam. They can also clear garrisoned buildings provided enough are attacking the fortified structure at once (and can survive the firepower that the defending troops will pour upon them as they approach).
Though these peculiar machines can easily devastate large groups of infantry units which in return will bolster the number of them at the Foehn commander's disposal, tougher infantry units such as Brutes will require multiple Duplicants detonating near them to initiate a successful assimilation for more copies. While the Clairvoyant is amphibious and can detect stealth, the Duplicant cannot and will only retain its ability to snuff out hostile infiltrators.