No its not a typo. It has been done by some ARF's in the past and present while not to common. I have been flying an older ARF called a Maqic Extra (Modeltech) for perhaps three years now and this did infact come setup with a double hard wire push/pull rod on the rudder, Just the rudder and I have no doubt it may also be used in some of the China Model Products airplanes also.

Its consists of a control horn on each side of the rudder with a hard wire pushrod on each side running in plastic tubes forward to attach on each side of a rudder servo horn. On mine I am using a older strandard sized JR digital and totally forgot which.

I suppose the idea is to have a totally stiff therefore fast rudder linkage with zero blowback but thats just my speculation and I,ve no idea if there is any real advantage or not. There is a disadvantage of course you must take great care in the mechanical setup and adjustment or your servo will sing and use up your battery supply rapidly. Once you do have a good setup it has proved no particular maintenance problem in that way and my linkages have been no problem now for the last three years and a lot of flights.

As far as the airplane "requires it" goes, certainly not there are many options in linkages that are open to you.

John