I'm currently working on a shop for a customer that sells and rents art. I'm using configurable products that have a rent or buy attribute. Due to the nature of the customer's business you can't rent an object (product) multiple times and you can only buy OR rent a product.
A configurable product consists of 4 simple products (3 for monthly renting options and 1 for buying).
Is there a standard (via configuration) way to prohibit adding one configurable product multiple times to the cart without using the inventory configuration/stock management (currently the scenario only works without deducting quantities from stock/inventory).