jpa整合问题：Unable to build EntityManagerFactory，怎么回事

hibernate-jpa2.0+spring3.2.3+tomcat7，本来好好的，忽然有一天出现这个问题，persistence.xml文件和applicationContext.xml文件未做过改动，jar包也没动过，到底是什么原因啊～
以下是错误列表，部分省略……
严重: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
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Caused by: javax.persistence.PersistenceException: [PersistenceUnit: CollierTrack_NET] Unable to build EntityManagerFactory
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Caused by: org.hibernate.DuplicateMappingException: Duplicate query mapping findAll
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