Thank you for reporting this.
If you are using latest version of Multichain these lines appear in two cases:
In getnewaddress API. In this case this message just reports that new address was created (key was added to the pool).
Or (more likely) when you call getinfo API. These message don't have any sense in this case - we inherited it from Bitcoin Core.
We'll remove them in both cases in the next version, they don't help anyway.
Please let us know if you don't call getnewaddress or getinfo and they still appear.