Symptoms
OpenLDAP has been added as a security provider. Error occurs when searching for OpenLDAP records in K2 workspace (i.e. Server Rights, etc. )
Diagnoses
When "Search For" is set to "Users" or "Groups", the search works as expected. But when "Search For" is set to "All", it throws the error "An entry with the same key already exists".
Resolution
This has been logged as a bug. Current workaround would be to set "Search For" to either "Users" or "Groups" when searching against OpenLDAP.