How to reproduce:
1. Open the attached “IN-81883“ project
2. Open the “SampleScene“
3. Enter Play Mode
4. Try to drag the “RedSquare” on the “WhiteSquare“
5. Try to drag the “WhiteSquare” on the “RedSquare“
6. Observe the Console window

Expected result: 'OnDrop' event is logged 2 times
Actual result: 'OnDrop' event is logged once

Reproducible with: 1.9.0 (6000.0.12f1), 1.10.0 (2021.3.42f1, 2022.3.42f1, 6000.0.15f1)
Not reproducible with: 1.8.2 (2021.3.42f1, 2022.3.42f1, 6000.0.11f1)

Reproduced on: Windows 10 (user), Windows 11 pro
Not reproduced on: No other environment tested

Notes:

• Also reproducible in Player
• The “RedSquare“ GameObject has the “PointerDown“ script with 'IPointerDownHandler' attached, the “WhiteSquare“ GameObject doesn’t