Type in Global in the filter of the content browser while being in content (it will choose all sub folders)
Filter by material collection
Find all cloned material parameters collections and one by one delete them with replace reference to 1 folder until they all materials and bp’s point to that 1 version of the file.
OrionGlobalGameplayCollection is the main culprit in most cases.
The thing is that the Global folder should probably be the same for all characters. That’s my assumption about the original paragon game. It’s all cloned to split out characters. This is the cause of the problem, but there is no tool to combine folders.