Changing a base price creates a douplicate record (P4106)

We'd like to change an existing base price with P4106.

Steps to reproduce:

1. there is one existing base price per item

2. inquire the base price and change the effective through date to yesterdays date

3. add a new price valid from today to system end date (automatically fill in the dates)

4. Save the changes

5. Check the base price: there are now three records:

     a) first existing record valid through system end date

     b) changed record (same price as in a)) with valid through date = yesterday

     c) new base price added in step 3.

How can we avoid to keep the first record - we just like to overwrite the valid through date for this existing price.