This is caused by the same thing that causes this:

FBlueprintEditorUtils::PromoteGraphFromInterfaceOverride is the cause of this behavior 

Steps to Reproduce
  1. Create an actor bp
  2. Add a function with an input and output
  3. Create a child BP that inherits from that
  4. Override the function 
  5. Select the function in the details panel
  6. Duplicate (CTRL + W)

Results: All input and output pins are doubled

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ComponentUE - Gameplay - Blueprint Editor
Affects Versions4.
Target Fix4.24
Fix Commit8126934
Main Commit8493028
Release Commit9552237
CreatedAug 16, 2019
ResolvedAug 20, 2019
UpdatedOct 28, 2019
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