You can use campaign priority to:
edit maximum CPC bids, tracking templates, or custom parameters and destination URLs for non-subdivided product groups
promote certain product groups across all your campaigns
determine which campaign’s bid to use for a product when the same product is included in multiple campaigns
subdivide campaign products according to freely-assigned values with custom labels
When you have the same product in multiple Shopping campaigns, you can determine which campaign should participate in the auction for that product with campaign priority. Your campaigns already have a priority: Low. But you can change this priority to Medium or High. These priorities determine the bid for any product that the campaigns share.
Read more here: https://support.google.com/adwords/answer/6275296?hl=en