Updates on the Salesforce Opportunities that are synced to the NetSuite Sales Orders are creating duplicate Sales Order Lines.
The first thing to check is to see if the Sales Order form being used has the Salesforce Line ID column field hidden on the Sales Order Lines. This Salesforce Line ID field is what helps the connector find and update existing Sales Order Lines.
If a column field on any record type in NetSuite is hidden, the Connector cannot map to it. If the Salesforce Line ID field is hidden, the connector cannot find and update the existing Sales Order Lines, so it creates new ones.