I am trying to load CSV using loader in Neptune. While loading modified data;
Below two scenarios I came across

1. Existing records don’t get replaced instead of replace array gets created for modified values
   2.Duplicate records are getting created having same node id.

To handle first scenario I got know about setting updateSingleCardinalityProperties to TRUE.
how I can tackle with 2nd scenario. And how duplicate nodes are getting created with duplicate node id(node id has to be unique globally)

Any help is appreciated.
Thanks in advance!!