Single/Pair Variation

Hello!! I need to create a product with two variation (single/pair). Imagine a jewelry store that sells the same product with these two options. The problem is that I need to create something that I could manage the stock of each variation correctly:

For example:

The product has 20unit quantity.

One customer order a single variation of it. Stock decreases 1unit as simple product.
Other customer order a pair variation. Stock should be decreases 2 units, but woocommerce take it as simple product, so It will take 1 unit.

Is there any plugin or code which can solve this?

Thank you!!