I think Prime Worf passing through the anomaly must have caused other Worfs to also start jumping across realities. Just look at all the Enterprises in the vicinity of the anomaly near the end. And what about all those different Worfs seen in the shuttle when Worf Prime flies back through it? Remember when Worf arrives in the reality where he's first officer and he and Deanna have kids, Data immediately asks him if he's noticed another discontinuity. To me, this proves that that reality's Worf had already been replaced by yet another Worf prior to the arrival of Worf Prime.....ah, it's confusing!