I am trying to do some cleaning.
Is there a way to find out in my answers' history (1500), if there is a another answer to the same post that has been accepted?
Here is example of why:
Mass deletion of posts is something that will generally get you suspended.
That being said, the SEDE (Stack Exchange Data Explorer) is the place to go if you want assistance in crafting such a query so you can study your acceptance rate and your scoring / ability to get the "check" which are all excellent and fine goals to have.