V3's bulk "Import Orders" feature does not allow a singular CSV field to be mapped to more than one Shipstation field.
There's many cases where the same field should/could be mapped to different places. Examples:
Name routed to Recipient Name and Buyer Name
Email Address mapped to Email Address and Username
Order Date mapped to Order Date and Paid Date
This is not a problem in the legacy layout, which means we have to switch back to V2 anytime we have a file to import. Or to unnecessarily modify a CSV file to include duplicate information.