Imagine this situation in distributed cache with 3 owners:
1) The segment X is owned by nodes A, B, C
2) Node B fails -> CH_UPDATE and then REBALANCE_START are broadcasted
3) Node D starts transfer of segment X from C
4) Node C fails -> another CH_UPDATE is broadcasted
5) D handes the CH_UPDATE and removes the transfer of segment X from C, but does not start another transfer from A

The addedSegments does not contain the restarted transfer, because all transfers from write consistent hash are removed from it in the beginning - the segment is considered received here although the transfer is still in progress.