XnView Software

XnViewMP 1.9.4
Windows11 (24H2), display resolution 3840x2160, dpi scale 150%

Viewer - paste toolbar

to reproduce
1. open any image in Viewer
2. copy any part of the image via Ctrl+C
3. press Ctrl+V to paste it multiple times, eg 2
copy will be pasted, but paste toolbar will appear twice
4. press Esc 2 times
app will crash

expected behavior
few options

• apply existing copy and paste new one in the same place
  
  OR

• use Ctrl+V combination to Apply action as there is no default shortcut (Enter opens Browser)
  behavior similar to Crop toolbar when pressing Shift+X

Related

• issues
  1.9.4 - viewer - paste toolbar - issues with multiple pasting (current post)

• suggestions
  Viewer - paste - improve pasting
  Viewer - crop toolbar - add rotation control
  Viewer - crop toolbar - add zealous crop
  - done -
  Ratio - improve naming and sorting (1.6.0)
  Viewer - crop toolbar - add shortcut to perform crop (1.5.0)

Thanks to your detailed description I can reproduce the problem.