No, at any point, only one promotion can be applied on a product. This is because when a product is scanned on the transaction grid, the application is smart enough to know if it is covered in more than one promotion(s) defined. If it is covered in multiple promotion(s), it checks the order in which the promotions should be applied. In cases where the order is NOT specified, the promotion that was created earlier (based on date / time) takes precedence.