Datasource creation wizard doesn't check uniqueness of datasource name or jndi during a creation, if already used name is specified it fails after the creation of a new datasource, ie. all user data are lost

How to reproduce
1) try to create new datasource with name "ExampleDS" 

Expected result: user will be notified about duplicit name being used before the creation process is done -- or allow user to correct the name (see BZ1027246)

Actual result: user will end up with error message and all data is lost