Hello,
If you want to copy a variant, I would rather recommend you to perform that action within the main product edition page.
While editing the product, in the "variant" tab, you can select a variant and duplicate it.
Copying a variant from the product listing would result in some issues since you will have two variants with the same characteristics.
The dedicated part for duplicating variant handle that and ask you to choose the characteristic values for the variant that you will create (and if the combination already exists, it will skip it)
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.