How can I prevent Quartz multiple execution after deploy

[zlzc2000]

hallo,

we have problem with Quartz.
Im using tomcat 5.5
i using 'localhost' to deploy a Spring project on server.
after deploy run Quartz once time,
but after tomcat restart, execute the same jobs twice at the same time.

how can i prevent it?
follow code are our server.xml code

...
<Host name="localhost" appBase="webapps"
unpackWARs="true" autoDeploy="true"
xmlValidation="false" xmlNamespaceAware="false">
</Host>

<Host name="XXX.com"
unpackWARs="true" autoDeploy="true"
xmlValidation="false" xmlNamespaceAware="false">
<Alias>www.XXX.com</Alias>
<Context path=""
docBase="/var/lib/tomcat55/webapps/xxx"
reloadable="true">
<Realm className="org.apache.catalina.realm.JDBCRealm"
driverName="org.postgresql.Driver"
connectionURL="jdbcostgresql://localhost:5432/xxx"
connectionName="postgres" connectionPassword="" userTable="users_password"
userNameCol="userid" userCredCol="password"
userRoleTable="user_role" roleNameCol="rolename"
digest="MD5"/>
</Context>
</Host>
...