Incorrect Tempo Estimation on exported Rhythm Track

### Bug description

If a User decides to create a rhythm track file, and export it via Audacity, the tempo estimation upon import of this file into a new project will be incorrect.

### Steps to reproduce

1. Launch Audacity
2. Create a rhythm track with BPM of 200
3. Export the file
4. Import the file into a new project
5. Observe the BPM to be calculated as 100 BPM, not 200.

### Expected behavior

The tempo should be detected as 200.

### Actual behavior

The tempo is detected as 100.

### Audacity Version

current master / alpha / nightly build

### Operating system

Windows, macOS, Linux

### Additional context

_No response_