That's what I heard when I moved to the area in the mid 90s. The ND warden would allow you your 4 SD fish if docked at Langliers maybe even Cattail or Beaver. I worked with a guy from Linton who is an avid angler, and this was his claim..THEN...not sure now. I didn't want to bring it up as it was so long ago, and it was just something I 'heard'.
With today's technology, gopro cameras and GPS trails, it would be pretty easy to document exactly where each fish was caught. It would be interesting for someone to document a limit in ND and SD then fight it out in court. Because logically, it should be legal to harvest a limit in each state without having to go home between trips.