Why do red guardian and bwdo have the same synergy with each other?

So their synergies with each other are exactly the same with no extra benefit of the doubling effect, i mean its a unique synergy but it seems like there is a mistake.



4
Comments
Since synergy does NOT extend down to all lower Star versions, it lets you get the synergy no matter which combination you have available.
5* RG with 3* BWDO, or 5* BWDO with 3* RG (for example, not sure where the Star cutoffs for that synergy is).