When the "Context Sensitive" option is checked, there is a duplicate menu item that appears in the Blueprint graph's right-click context menu for every "Add Component" menu action.
Unchecking "Context Sensitive" will remove the duplicate menu item.
This does not occur in the 5.0.x release.
N/A
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-170888 in the post.