How to efficiently merge two dictionaries in Python without duplicates?

I'm working on a Python project where I need to merge two dictionaries, but I want to ensure that there are no duplicate keys as the end result should contain unique keys with their corresponding values. Here's what I've tried:

dict1 = {'a': 1, 'b': 2}dict2 = {'b': 3, 'c': 4}

merged_dict = {**dict1, **dict2}

This approach overwrites the value of duplicate keys, but I'm looking for a way to either prevent duplicates or handle them in a specific manner (e.g., by adding the values together or keeping the higher value).

I've searched for solutions, but most methods don't address handling duplicates in the way I need. Is there an efficient Pythonic way to merge dictionaries while managing duplicates according to custom logic?

Environment: Python 3.8 on Ubuntu 20.04