OnTriggerEnter2D / OnTriggerExit2D clarification

Hi there.
Instead of a long verbal description I prepared a little scene and a big gif

Code (csharp):

1. using UnityEngine;
2.  
3. public class Trigger : MonoBehaviour
4. {
5.     [SerializeField]
6.     private int _counter;
7.  
8.     private void OnTriggerEnter2D(Collider2D collision)
9.     {
10.         _counter += 1;
11.     }
12.  
13.     private void OnTriggerExit2D(Collider2D collision)
14.     {
15.         _counter -= 1;
16.     }
17. }

As you can see I have a polygon collider which is a trigger and I count entries and exits of another collider. Somehow it appears that eventually the number of entries exceeds the number of exits.
I wonder why Unity triggers yet another enter of the collider if it's already within?
Summoning @MelvMay in thread

 

Nope?

 

I won't let my question die in this abyss. So, bump.

 

Something tells me that @MelvMay is on vacation and that's the reason why he's keeping silence since the end of July.
Anyway I bump this thread just in case.

 

Ok, thanks. I'll send the scene I used to capture the gif with a bug report.

 

well.. this "anomaly" is in unity since version 4.5 or even earlier. I know because it made me crazy and the development of one of my games to hell.. With every new unity version I check if it's fixed.. Continuous instead discrete tracking might help, but this will still happen in rare occasions.

 

Thanks. Now I can get rid of my workaround.