Constructor of a viewScoped class invoked twice - jsf-2

Question

I've been struggling with this for two days with no success and I think it's already time to ask for your help. But first of all, this is what I'm using:
JSF 2 Mojara 2.1.1
Primefaces 3.4.2
Netbeans 7.1.1
Tomcat 7.0.37
And now, the problem: I have a main page which is composed by several other pages using several <ui:include .. /> tags, like this:
<ui:composition template="/resources/templates/template1.xhtml">
<ui:define name="appData">
<p:panelGrid columns="1" id="contenidoAplicacion" styleClass="noborder">
<h:form id="fNewPerson">
<p:panel header="New employee" style="min-height:40em">
<ui:include src="./forms/personal.xhtml" />
<p:accordionPanel styleClass="noborder" activeIndex="3">
<p:tab id="tabSomeData" title="Identidad profesional" >
<ui:include src="./forms/formSomeData.xhtml" />
</p:tab>
....
....
</ui:define>
</ui:composition>
The personal.xhtm file looks like this:
<p:panelGrid>
<p:row>
<p:column >
<h:outputLabel value="Field1"/>
<p:inputText label="Field1" id="field1" value="#{dataBacking.selectedPerson.field1}" tabindex="1"
required="true" size="10" >
<f:convertNumber for="field1" integerOnly="true" groupingUsed="false"/>
</p:inputText>
<p:inputText id="field2" value="#{dataBacking.selectedPerson.field2}" tabindex="2" required="true" size="1" maxlength="1" >
<p:ajax event="keyup" listener="#{dataBacking.check}"
process="field1 field2" partialSubmit="true"
update="field1 field2 photo"/>
</p:inputText>
</p:column>
<p:column rowspan="5" >
<p:graphicImage id="photo" value="#{dataBacking.selectedPerson.photo}" width="90" />
</p:column>
</p:row>
...
</p:panelGrid>
The check() method in the dataBacking class is irrelevant because it only checks if the field1 and the field2 meet some rules and it works properly. The problem comes when the main page is loaded for the first time. In that case, the <p:ajax /> component in personal.xhtml doesn't work. I have to reload the page (simply by pressing the F5 key) and this time it works as it would be expected.
I've been changing some attributes of the component, but nothing seems to work. I really don't know what else to do. Any kind of help will be apreciated.
EDITED. After one more day, I think the problem has nothing to do with Primefaces ajax component, as the title of the question suggested. I've come to this conclusion through these two facts:
The behaviour with the <f:ajax .../> component remains the same.
I've figured out that the view relative to the first time I load the page is not persisted. I'll try to explain myself.
The DataBacking class has defined its scope as view so that the page can "see" all the attributes and methods during the time it's been shown to the user. However, I've noticed that the constructor is called twice: the first time the page is loaded (and then, none of the methods of the class are successfully invoked) and when I refresh the page. In this last case, the behaviour of both the page and the class is the expected one.