The best way would be to export a product from Shopify so you have the correct csv format. Then it would be a matter of duplicating the rows. Be careful you create a new handle for each new product as if you use the identical one it will override it on Shopify. You would need to add image links or go back into imported products and upload them. But at least all the identical data is already there so no need to copy and paste it in.
Thankyou so much for responding and helping me with this… is there any documents you can share as test cases so i can understand the format on how to apply this.