Error occurs during Oracle database initialization

Oracle error occurs during first time initialization.

Failed updating schema while executing query "create sequence xwiki.hibernate_sequence"
java.sql.SQLException: ORA-00955: name is already used by an existing object

at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:112)
at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:331)
at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:288)
at oracle.jdbc.driver.T4C8Oall.receive(T4C8Oall.java:743)
at oracle.jdbc.driver.T4CStatement.doOall8(T4CStatement.java:207)
at oracle.jdbc.driver.T4CStatement.executeForRows(T4CStatement.java:946)
at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1169)
at oracle.jdbc.driver.OracleStatement.executeUpdateInternal(OracleStatement.java:1615)
at oracle.jdbc.driver.OracleStatement.executeUpdate(OracleStatement.java:1580)
at org.apache.commons.dbcp.DelegatingStatement.executeUpdate(DelegatingStatement.java:225)
at org.apache.commons.dbcp.DelegatingStatement.executeUpdate(DelegatingStatement.java:225)
at com.xpn.xwiki.store.XWikiHibernateBaseStore.updateSchema(XWikiHibernateBaseStore.java:410)

please, see attached log file for more details.

Steps to reproduce:
1)create brand new db schema (xwiki)
2)copy xwiki-enterprise-web-1.2-rc-3.war into tomcat container
3)edit hibernate.cfg.xml (uncomment Oracle DB connection)
4)go to http://localhost:8080/xwiki web page
5) see xwiki.log file for more error details