If it's parsed the following example:

package main

// inline comment.
const a=3

It is returned 4 nodes having Comment role instead of only one

• internal_type: CommentGroup
  internalRole: Comments
  roles: Comment, List
• internal_type: CommentGroup
  internalRole: Doc
  roles: Comment, List
• internal_type: Comment
  internalRole: List
  roles: Comment

addendum:
This issue might be related to these similar ones in other languages drivers:
bblfsh/javascript-driver#36 bblfsh/python-driver#167 bblfsh/java-driver#86