Copy-paste by dragging makes measures with voices corrupted

Issue type

File corruption

Description with steps to reproduce

1. Create new score using treble clef template and set time signature to 3/4
2. Add a half note and a quarter note to voice 1.
3. Add a quarter note and a half note to voice 2.
4. Now drag one measure onto the other with the mouse.
5. Save the file. A corruption message will appear.

I think this needs to be fixed, no matter how dumb the reproduction steps may be.
Not a regression. The issue is present since 4.5.0 (when copy-paste by dragging feature was introduced)

Supporting files, videos and screenshots

https://github.com/user-attachments/assets/93ff8f37-cb28-47b5-ab16-eb483db288af

In which versions of MuseScore Studio is this issue present?

Musescore 4.5.0 - 4.7.0 master

Regression

No.

Operating system

windows 10

Additional context

The issue was found while investigating https://musescore.org/en/node/387308

Checklist

• This report follows the guidelines for reporting bugs and issues
• I have verified that this issue has not been logged before, by searching the issue tracker for similar issues
• I have attached all requested files and information to this report
• I have attempted to identify the root problem as concisely as possible, and have used minimal reproducible examples where possible