It depends on what you are trying to do. Why using different handlers for each human task? You can do it using <task>, but I recomend you to read and understand
http://docs.jboss.org/jbpm/v5.1/userguide/ch.Human_Tasks.html
and see if you are following the right approach, you can also take a look at this simple test that has two simple human tasks,
https://github.com/calcacuervo/JBPM5-Samples/blob/master/human-tasks/src/test/java/com/test/HumanTaskTest.java
Demian