product e-configurator issue in Siebel 15.18.0.0

We are facing below product e-configurator issue in Siebel 15.18.0.0

Issue Replication steps:

1. Agent A logins to Siebel Application

2. Opens a pending Sales order and click on "Configure" button

3. After this e-configurator screen comes up and Agent A does the required operation there.

4. While Agent A is still on the e-configurator screen for the order, another Agent B logins to Siebel application with different login Id 

and cancels the aforesaid order and order becomes cancelled.

5. Now at the same time Agent A continues the process on the configuration screen, completes the process and clicks the "Done" or "Cancel" button, flow comes to Order screen, but the Order status is again "Pending" instead of "Cancelled" (Agent B already cancelled the Order in different session)