Endless updating of field definitions

On the homepage template the definition within box/declarations.inc sets this:

<content:declareField name="title"
title="Title" type="SmallText"
titleKey="blog.title" bundleKey="<%=resBundleID%>"
aliasNames="boxTitle"
/>

and common/main_content.jsp sets this:
<content:declareField name='content' title="Content"
titleKey="mainContent.content" bundleKey="<%=resBundleID%>"
type="BigText"
aliasNames="contentContent"
/>

On another page template, where box and main_content is not included, a customer sets this in his own container list:

<content:declareField name="title" title="Title" type="SmallText"
value="Lord of the Flies" />

<content:declareField name="content" title="Content" type="BigText" />

According to the database tables jahia_fields_def_prop, the field definition could be different for different page templates (although it is not advised to do so). The difference in the title and default Value is not the problem here, the current Jahia 5 seems to be able to handle that, the problem is only the aliasNames field. This property is causing that the definitions are always redefined.