Corporate Spin-off

Wesfarmers have set up Coles as a separate security giving share holders the same number of shares in the new company.  Not being a financial genius, I always find these sort of transactions very difficult.  I am assuming I enter this as a Corporate Spin-off.  Using the template to do this, it asks for the company name which I have entered as Wesfarmers and then the new company name which I have entered as Coles (it does not ask you to set it up as a new security).  It then asks the number of shares, cost of old share and cost of new share.  I think I am on the right track as  adding the 2 figures together comes to exactly the amount of the Bulk Redemption Upload Price.  My problem is that when I click done, it says that the security name is already in use, choose a new one.  Grateful for any help with this.