Yes there is. I don't know where it is listed but I seem to remember that it was about 520 or 550 by Scott Stokley. I did look under WFDF records but they don't make any designation as to backhand or sidearm. I'd try a Google search under Scott Stokley or Gregg Hosfeld (I believe Hosfeld did have a site listing golf records a while back). Good luck
Stokely came and did a demo at our course when I was a newbie, about 1999. He was (I believe) the distance record holder (backhand) at that time. When he was showing us his techniques he threw both backhand and sidearm. In my recollection his sidearm was VERY near to his backhand distance wise. I dont think at that time, or even now there was/is a distinction between the throw you do, only the distance. I think there should be, and if there is, I am anxious to see!
His sidearm record is 541' with a X-Clone...think if he ever got his hands on any of the new Discraft plastic during his prime!! His backhand was around 650'...that record held from 95' to 02' when Max Voight broke it with a XS
I think he may have smashed that 541' record during that heavy wind year at Big D in the desert. Not 100% but I think he may have gotten off a 700'er. I remeber his girlfriend throwing a 1/4 mile roller that year. It was VERY windy.
Sam or Chicken at Innova would know for sure.