p: growl of primefaces is showing twice the CPF name

My p: growl of primefaces is showing twice the CPF name when cpf is invalid. I'm using bean validation.

<p:outputLabelfor="cpf" value="CPF"  rendered="#{cadastroClienteBean.CPF}"/>
                    <p:inputMask id="cpf" label="CPF" mask="999.999.999-99"  placeholder="___.___.___-__"
                                 value="#{cadastroClienteBean.cliente.documentoReceitaFedral}" size="14"
                                 rendered="#{cadastroClienteBean.CPF}" required="true" 
                                 requiredMessage="CPF deve ser informado">
                    </p:inputMask>





@CPF
@Column(name = "doc_receita_federal", length = 14)
public String getDocumentoReceitaFedral() {
    return documentoReceitaFedral;
}