If your miner accidentally finds a share that has already been submitted by your co-miner, this share will be marked as a duplicate and rejected by the pool. In the previous version, the pool would go further and terminate yoour connection.

Connectivity issues are the most common reason for this to happen.

Our new release added the solution to this issue and now duplicated shares can't be submitted. You can always check your account's stats to confirm accepted/rejected shares.