Version tested: 2022.2.0a12

Steps to reproduce:

1) Open attached project, VFXShadowsTest scene
2) In HDRP set Max Screen Space Shadows to 4
3) Observe that the scene has 4 lights: dir (1 slot), point (1 slot), spot (1 slot), area (2 slots)
4) in Rendering Debugger/Light enable ScreenSpaceShadows debug mode
5) Scrub Screen Space Shadow Index and observe that the same dir light shadow is bound to indices 0 and 1

Bonus to this bug

We have 4 lights (5 slots) but area light shadows start looking correctly only when we allocate 6 shadow slots in settings. As Anis has explained memory slots are allocated in chunks of 4 and area light inefficiently allocates itself in the second chunk (because it can't span over two memory chunks, from slot 4 to 5).