Copy and Paste does not work as advertised

### Bug description

Everything I have tried does not allow me to paste over/overlap the selected area. It just pastes it into an adjacent area. Am I missing something, or is this a bug?

### Steps to reproduce

1. Pasting behaviour set to overlap
2. Area copied
3. Select the area to overlap
4. Utilise the paste and overlay option
5. It pastes it adjacent to the area I want pasted over.

### Expected behavior

For it to overlap the selection and not move the selection, and paste the data adjacent to it

### Actual behavior

Pastes the data adjacent to the selected region.

### Audacity Version

Audacity 4.0.0

### Operating system

macOS, Linux

### Additional context

_No response_

Reproduce the issue on macOS or Linux with Audacity 4.0.0 using overlap paste: copy an area, select the destination, and use the paste and overlay option. Trace the paste behavior that places the data adjacent to the selection and compare it with the documented overlap behavior. Done means the pasted data overlaps the selected region without moving the selection.

Written by the indexing model from the issue text.