can magento have configurable product with 1 sku and multi variation ?
Can you go more into your requirements, please?
Magento uses configurable products to allow customers to choose between multiple physical products that each have their own SKU to track stock.
If you do not need to manage stock but want customers to choose between variations, this instead could be achieved with a siple production that has custom options on it. http://docs.magento.com/m2/ce/user_guide/catalog/settings-advanced-custom-options.html
Are you looking for answers for Magento 1 or Magento 2?