Support:
The theory was convincing, the reality, not so much!

I advised my client to use the finder to select the document they want. However here's what happens: If there are 2 documents with the same document number and they want the 2nd one, they highlight it and select it. The Find dialogue box shows the correct Customer name and looks correct. However as soon as the "Ok" button is selected, the first match in the list is used and that Customer becomes the current one. I've been able to reproduce this in sample data.