Updates to Salesforce Opportunities that are synced to the NetSuite Sales Orders are creating duplicate Sales Order Lines.
Verify the Sales Order form being used has the Salesforce Line ID column field hidden on the Sales Order Lines. The Salesforce Line ID field allows the connector to find and update existing Sales Order Lines. If a column field on any record type in NetSuite is hidden, the Connector can't map to it. If the Salesforce Line ID field is hidden, the connector can't find.
Another option is to map the externalID to an alternate field to identify unique records with a lookup.