Not duds, expended submunitions carriers. Since cluster bomb carriers just expel their payloads, the remnants tend to survive and clutter up the place.
As you see, there were thousands of rounds of this inaccurate, unguided stuff fired into the city of Kharkiv, pretty much from the first day of the invasion. And who knows where else.
They are terrible weapons and should be outlawed. We dropped a half a million tons on Vietnam and have left them strewn about Bosnia, Iraq and Afghanistan. Now we’re leaving our legacy for the Ukrainian children.