They have had soemthing similar for a long time. many law enforcement agencies have a 12 ga. round that fires two large ball bearings connected by a short cable. The reasoning for that round was yu could open a hole through a door and then fire a regular round through, assuming your target was foolish enough to stand by the hole. Obviously, its intended use is quite different than that suggested.
I suspect, without knowing the ballistic info behind this new round, it would lose too much of its stopping power, the range of the round would certainly be lessened. No doubt it would hurt like heck, possibly maim, but I don’t think it would be all that effective at flat out stopping. I think it would be useless in the hostage scenario they suggest.
Now a 12 ga. or even a 40mm grenade launcher with a device that expanded even further that could wrap around a perp might be something. I know one of the villians on the Tick had one and assuming television hasn’t lied to me, it could work.
Multi piece small arms ammunition has been around since at least the American Civil War (search Shaler bullet). They were of larger calibers .54 & .58 and didn’t work that well then. They were very inaccurate, lacked stopping power and the soldiers who were issued them seem to have been more likely to throw them away than to fire them.
The earliest example I know of comes from the days of warships with sails and black-powder cannon. Two cannon balls joined by a length of chain were fired into another vessel's sails These would cut ropes, entangle all sorts of rigging, and possibly bring down masts.