Conditional Sum 2 columns

Hello. Hope someone could help me with my problem.

I have 2 columns of data that is changing everday. It may be "original" or "reduced". And I want to get the sum of the "original" or "reduced" but not redundant. How to make a automated sum formula for this? (kindly refer to the photo of what I want to be the result).

Thank you so much.

Sum with conditions.PNG

Thank you so much!