TYPO3 Core

This behaviour occurs in TYPO3 4.4.9 as well.

Reproduction steps:
1. Create a test workspace
2. Live space: Create a page
3. Live space: Create two content elements within the new page
e.g.:
- Test1
- Test2

4. Change to test workspace
5. Test workspace: Move down the first element (Test1) - this works
e.g.:
- Test2
- Test1

6. Test workspace: Move down the second element (Test2) - this fails, the order does not change

Just guessing why:
The bug might be within the method t3lib_TCEmain::getSortNumber. It seems like the sorting relies on the sorting value from the live versions. That would explain why moving around a single item works fine, but when moving a 2nd item it fails.