It's​‍​‌‍​‍‌​‍​‌‍​‍‌ a hard challenge if you try to convert several VCF files manually. What you really need is a tool that can bulk export vCard to CSV and merge all entries into one single spreadsheet. I had over 600 scattered files and wanted to make a single structured CSV for CRM import. The only way I managed to do it was with OSTtoPST VCF to CSV Converter that reads all VCFs automatically and produces one consolidated CSV without duplicates. You can also preview the fields before exporting, which is great. If your contacts are in a valid VCF format, the converted CSV will be neat and good to ​‍​‌‍​‍‌​‍​‌‍​‍‌go.
More info: https://www.osttopstapp.com/vcf-to-csv.html