Problem with content container lists in new template

Hello everybody, 

I have a strange problem with a new page using a new, quite simple template
(a page with a html header, a main_content and a box container list).

Here my actions and the problems that occur then :
1.	I created new page with my new template & committed the changes in
the workflow
2.	I tried to access/open the page: ERROR on the page: 

Error :
Error while forwarding a Jahia engine's content, Root cause : Error while
forwarding the Engine
/jsp/jahia/templates/myjahiasite/my_templates/my_conference.jsp : Cannot
update fields definitions in the database, Error in
db_update_field_definition : Invalid argument value,  message from server:
"Duplicate entry '103' for key 1" -> BAILING OUT, root cause:Cannot update
fields definitions in the database, Error in db_update_field_definition :
Invalid argument value,  message from server: "Duplicate entry '103' for key
1"

Exception StackTrace: Cause level : 0 (level 0 is the most precise
exception)
org.jahia.exceptions.JahiaException: Cannot update fields definitions in the
database, Error in db_update_field_definition : Invalid argument value,
message from server: "Duplicate entry '103' for key 1"
	at
org.jahia.services.fields.JahiaFieldDefinitionsDB.db_update_field_definition
(JahiaFieldDefinitionsDB.java:391)
	
(in Catalina.out, there are even some more errors before this one, all being
like 'Duplicate entry '94' for key 1' )

3.	I open the new page again in edit mode: ERROR concerning the main
content (the content and the box container lists), the rest displays okay:

Error :
Error while forwarding a Jahia engine's content, Root cause : Error while
forwarding the Engine
/jsp/jahia/templates/myjahiasite/my_templates/my_conference.jsp : No bean
found under attribute key boxContainerList -> BAILING OUT, root cause:No
bean found under attribute key boxContainerList

Exception StackTrace: Cause level : 0 (level 0 is the most precise
exception)
javax.servlet.jsp.JspException: No bean found under attribute key
boxContainerList
	at
org.apache.struts.taglib.logic.CompareTagBase.condition(CompareTagBase.java:
221)
 
(in catalina.out, there is also the following before the above message:

error in db_create_container_definition: Invalid argument value, message
from server: "Duplicate entry '55' for key 1"
ERROR - Error:
org.jahia.exceptions.JahiaException: Container not declared :
boxContainertest_1, Container not declared : boxContainer test_1

ERROR - Couldn't find any object with name contentContainerList

+ several times this one:
Error in db_create_container_definition : Invalid argument value,  message
from server: "Duplicate entry '56' for key 1"
ERROR - Error:
org.jahia.exceptions.JahiaException: Cannot insert new container definitions
in the database, Error in db_create_container_definition : Invalid argument
value,  message from server: "Duplicate entry '56' for key 1"
	at
org.jahia.services.containers.JahiaContainerDefinitionsDB.db_create_containe
r_definition(JahiaContainerDefinitionsDB.java:272)

4.	after switching to live mode, back to edit, change languages, reload
etc repeatedly: it finally loads the 2 containers correctly.

5.	but when adding a new main_content container, no error, but it
displays several other containers (some with text in it) before mine. and
adding a box container creates an error:

Error while forwarding a Jahia engine's content, Root cause : Error while
forwarding the Engine
/jsp/jahia/templates/myjahiasite/my_templates/my_conference.jsp : Null
property value for 'field(boxTypetest_2)' -> BAILING OUT, root cause:Null
property value for 'field(boxTypetest_2)'


Exception StackTrace: Cause level : 0 (level 0 is the most precise
exception)
java.lang.IllegalArgumentException: Null property value for
'field(boxTypetest_2)'
	at
org.apache.commons.beanutils.PropertyUtils.getNestedProperty(PropertyUtils.j
ava:755)
	at
org.apache.commons.beanutils.PropertyUtils.getProperty(PropertyUtils.java:80
1)


Here is how I include the 2 container lists in my template:

<jsp:include page="include/main_content.jsp" flush="true">
            <jsp:param name="id" value=" test_1"/>
        </jsp:include>
<jsp:include page="include/box.jsp" flush="true">
            <jsp:param name="id" value="test_2"/>
            <jsp:param name="displayDetails" value="false"/>
        </jsp:include>


Does anybody have an idea on what the problem is here?
And also, where can I find the entries that are said to be duplicate?

Many thanks,
Juliette