Cluster with non-shared JDBC cache store has too much entries after node failure

In resilience test with 4-node cluster where one node is killed a weird situation appears. Before the node kill have this number of entries:

210602;215820;209400;203038 = 838860 entries

After the kill the number of entries changes for a while:

210602;null;209400;203038
250602;null;269400;243038
290602;null;269400;273038
300602;null;289400;293038
300602;null;289400;293038
321218;null;296035;293038

But then it stabilizes on

326899;null;305039;314165 = 946103 entries

When the node02 is restarted it complains about duplicit entries:

ERROR [org.infinispan.loaders.jdbc.stringbased.JdbcStringBasedCacheStore] (OOB-124,null) ISPN008024: Error while storing string key to database; key: '8Az4Ia2V5NzYzNDI=', buffer size of value: 1050 bytes: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Duplicate entry '?8Az4Ia2V5NzYzNDI=' for key 'PRIMARY'

Is this a bug or wrong configuration?

Here is an excerpt from configuration (sorry for no formatting):
<distributed-cache batching="false" indexing="NONE" l1-lifespan="0" mode="SYNC" name="memcachedCache" owners="2" remote-timeout="60000" start="EAGER" virtual-nodes="512">
<locking acquire-timeout="3000" concurrency-level="1000" isolation="REPEATABLE_READ" striping="false"/>
<transaction mode="NONE"/>
<state-transfer enabled="true" timeout="600000"/>
<eviction max-entries="-1" strategy="NONE"/>
<string-keyed-jdbc-store datasource="java:jboss/datasources/JdbcDS" passivation="false" preload="false" purge="true" shared="false">
<property name="databaseType">MYSQL</property>
<string-keyed-table prefix="node01">
<id-column name="id" type="VARCHAR(100)"/>
<data-column name="value" type="BLOB(1200)"/>
</string-keyed-table>
</string-keyed-jdbc-store>
</distributed-cache>