Unique model in a product

Is there any way to make the option "model" when I add a new product to be unique. I dont want an extension that automatic generate model, i want to put model by myshelf and to be unique, because by my mistake sometimes i put the same model twice. Have you got any idea how to solve it? Thnx a lot in advaced

No idea if that can be done but you can export your products as a csv file and then manually check the Model column to see if you have any duplicates?