Can I upload into a catalog more than one row with the same ID?

Hello iarapodjarny Currently, It is not possible. The catalog Id must be unique.

What you can do is create an additional column lets says SKU and then use it to upload same product with multiple promotions.

Then you will have to manually check the validity of dates in liquid tag to render them in a message.

You can find more info on catalog here: https://www.braze.com/docs/user_guide/personalization_and_dynamic_content/catalogs/catalog/#preparing-your-csv-file:~:text=The%20first%20column%20of%20the%20CSV%20file%20must%20be%20a%20header%20of%20id%2C%20and%20each%20item%E2%80%99s%20id%20must%20be%20unique.