I've found the example VRT file to import a CSV file containing point data and have been using that quite a bit. Is it possible to import line and polygon data from a CSV file? If so, what are the VRT file tags to do that? Is there any additional documentation on the VRT file tags?
When you select the Add File... item twice, it will duplicate the entries in the Import node.
It does this by itself. See video -
After viewing the steps you use to Add the File, we see that the Features are added twice when you use the "Selected Files" option.
If you collapse that field, and just allow the file to be added from the File name: field, the Features are only added to the Import node once.
This has been reported in Defect # 388403 [Map Interoperability], and will be addressed the Development staff.