It appears that the DT native plugin registered in system32 (for the browser under use) is not updated until uninstalling the JRE
This issue occurs when the JRE installed via DT flow only

*** Tested Configurations:
- x86 Vista/ IE 8
- x86 Win 7. IE 9
- staging fcs dtoolkit.xml (from the mirror java.com)

*** Steps to reproduce:
0) Uninstall all JREs and DT plugin from the test system
1) Install jre 7u9
2) Uninstall jre 7u9
3) Set the registry key to use the staging dtoolkit.xml (which serves the 7u10 co-bundle)
HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Deployment Toolkit
 URLOverridre http://star-wip.sfbay.sun.com:88/inc/dtoolkit.xml

4) At this point, both deployJava1.dll and npdeployJava1.dll (under /system32) should have version 7u9
5) Using Firefox to invoke a JavaFX app from 2.2.4 deploy scrum
http://jfx.us.oracle.com/hudson/view/2.2.4/job/2.2.4-deploy-scrum/20/label=windows-i586-14/artifact/artifacts/apps/ga-samples/BrickBreaker.html

6) Follow the DT flow to install 7u10. The BrickBreaker applet should load fine

7) Close Firefox

- Go to system32, if will see npdeployJava1.dll is still from 7u9 but deployJava1.dll is from 7u10.
npdeployJava1.dll is updated to 7u10 if jre 7u10 is removed from the system.
- In similar fashion, of using IE in step 5, the same issue can be said to deployJava1.dll