Demonstration of the conflict:
1. Start by opening a data file and opening an account register.  For this example use a current asset account named "Checking at My Bank".
2. Highlight an existing transaction.  For this example use a transfer to another account named "Savings at My Bank"  The example transaction has a description, say "Deposit to Savings".  It has today's date and text, say "Print" in the Num field.  The text in the num field is critical for this demonstration.
3.  Move the focus to the line containing the other account name which we said was "Savings at My Bank" in our example.
4. Right click on that line and select "Jump" to the register of the account named "Savings at My Bank".
5. Place the focus in the Description field and add a character to the description.  To make it easy to remember, add an "X" at the end.
6. Using Tab or another method that does not commit the edit, move the focus to the line containing the other account name which we said was "Checking at My Bank" in our example.
7. Right click on the memo field in that line and select "Jump" to the register of the account named "Checking at My Bank".
6. Staying in this transaction, move the focus to the Num field, which we said contained the text "Print".  Remember that text in this field is critical to this demonstration.
9. Click on the Duplicate icon in the menu bar.  A pop-up will appear to fill in with a date and nothing in the num field.  Accept the defaults by clicking "OK".  The new transaction appears with the focus in the empty Num field.
10. The first artifact of the conflict appears at this point.  Hitting any number or text key does nothing in the new transaction's Num field.  For this example, say that we try to type "1234" in the num field.
11. Since we do want to change the number to something different to distinguish this new transaction from the the original, we use the mouse button 1 to move the focus to the description field, then return the focus to the num field.
12. This time we enter a different number, say "9876".  The number appears as desired.  Commit this edit by pressing the Enter key.
13.  After all this work we want to save our work so click on the "Save" icon in the menu bar.
14.  As expected, a pop-up appears warning that there is a pending edit in the account named "Savings at My Bank".  Cancel out of the Save.
15. Click on the account tab for the register named "Savings at My Bank".  Here we see the second artifact of the conflict.  Note that there is some garbage in the highlighted transaction that strongly resembles the "1234" keystrokes from the failed attempt to edit in the other register.
16. In an effort to resolve this dilemma, we cancel the pending edit by using the mouse button 1 to try to move to another transaction causing the pop-up warning which we then use to discard the changes.  Note, however, that the edit that we had originally left pending (the "X" at the end of the description) is discarded but the"1234" garbage that appeared while mucking around in the other register is saved.

The correct behavior should be to leave the first pending edit untouched while working on the second edit.  Garbage should not appear. 
The key to fixing this bug may lie in finding out why it is not possible to enter characters in the second transaction until the focus is moved out of the num field where it appears when the new transaction is originated. 

Note however that if there is a number in the num field while duplicating a transaction the default for the number is the next number for that register and there is no resulting conflict like I am describing here.