html <a> tag is closed twice broking links (for attachments only)

XHTML is invalid
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below is the feedback from the w3c webapp.

This page is not Valid XHTML 1.0 Strict!
Below are the results of checking this document for XML well-formedness and validity.
Warning Line 90 column 110: character "&" is the first character of a delimiter but occurred as data.
...ementEtComptesUtilisateurs?xpage=code&">Code</a></span><span class="xwikisep"
This message may appear in several cases:
You tried to include the "<" character in your page: you should escape it as "<"
You used an unescaped ampersand "&": this may be valid in some contexts, but it is recommended to use "&", which is always safe.
Another possibility is that you forgot to close quotes in a previous tag.
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Warning Line 91 column 130: character "&" is the first character of a delimiter but occurred as data.
...nementEtComptesUtilisateurs?xpage=xml&">XML</a></span><span class="xwikisep">
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Error Line 114 column 36: character "+" is not allowed in the value of attribute "id".
<h3 class="heading-1-1"><a id="Votre+compte" name="Votre+compte">Votre compte</a
It is possible that you violated the naming convention for this attribute. For example, id and name attributes must begin with a letter, not a digit.
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Error Line 114 column 56: character "+" is not allowed in the value of attribute "name".
<h3 class="heading-1-1"><a id="Votre+compte" name="Votre+compte">Votre compte</a></h3>
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Error Line 116 column 36: character "+" is not allowed in the value of attribute "id".
<h3 class="heading-1-1-1"><a id="Les+r%C3%A9pertoires" name="Les+r%C3%A9pertoire
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Error Line 116 column 64: character "+" is not allowed in the value of attribute "name".
...a id="Les+r%C3%A9pertoires" name="Les+r%C3%A9pertoires">Les répertoires</a><
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Error Line 118 column 37: character "+" is not allowed in the value of attribute "id".
<h3 class="heading-1-1-1"><a id="Pour+aller+sur+hotmail..." name="Pour+aller+sur
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Error Line 118 column 70: character "+" is not allowed in the value of attribute "name".
...Pour+aller+sur+hotmail..." name="Pour+aller+sur+hotmail...">Pour aller sur ho
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Error Line 120 column 33: character "+" is not allowed in the value of attribute "id".
<h3 class="heading-1-1"><a id="Le+r%C3%A8glement+g%C3%A9n%C3%A9ral+de+l%27%C3%A9
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Error Line 120 column 94: character "+" is not allowed in the value of attribute "name".
...%C3%A9ral+de+l%27%C3%A9cole" name="Le+r%C3%A8glement+g%C3%A9n%C3%A9ral+de+l%2
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Error Line 123 column 110: end tag for element "a" which is not open.
...lements.doc" />reglements.doc</a>, <a href="/xwiki/bin/download/Cours/En
The Validator found an end tag for the above element, but that element is not currently open. This is often caused by a leftover end tag from an element that was removed during editing, or by an implicitly closed element (if you have an error related to an element being used where it is not allowed, this is almost certainly the case). In the latter case this error will disappear as soon as you fix the original problem.
If this error occured in a script section of your document, you should probably read this FAQ entry.
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Error Line 123 column 223: end tag for element "a" which is not open.
...lements.sxw" />reglements.sxw</a> et <a href="/xwiki/bin/download/Cours/
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Error Line 123 column 338: end tag for element "a" which is not open.
...lements.pdf" />reglements.pdf</a><p class="paragraph"/>Dans le cas (peu
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Error Line 123 column 768: end tag for element "a" which is not open.
...lexion.doc" />feuille_de_reflexion.doc</a>, <a href="/xwiki/bin/download
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Error Line 123 column 901: end tag for element "a" which is not open.
...lexion.sxw" />feuille_de_reflexion.sxw</a> et <a href="/xwiki/bin/downlo
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Error Line 123 column 1036: end tag for element "a" which is not open.
...lexion.pdf" />feuille_de_reflexion.pdf</a>.<p class="paragraph"/>Finalem
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Error Line 123 column 1275: end tag for element "a" which is not open.
....doc" />Je_n_ai_pas_fait_mes_devoirs.doc</a>, <a href="/xwiki/bin/downloa
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Error Line 123 column 1423: end tag for element "a" which is not open.
....sxw" />Je_n_ai_pas_fait_mes_devoirs.sxw</a> et <a href="/xwiki/bin/downl
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Error Line 123 column 1573: end tag for element "a" which is not open.
....pdf" />Je_n_ai_pas_fait_mes_devoirs.pdf</a>.
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Error Line 124 column 33: character "+" is not allowed in the value of attribute "id".
<h3 class="heading-1-1"><a id="Le+r%C3%A8glement+sp%C3%A9cifique+de+la+salle+inf
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Error Line 124 column 99: character "+" is not allowed in the value of attribute "name".
...ue+de+la+salle+informatique" name="Le+r%C3%A8glement+sp%C3%A9cifique+de+la+sa
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Error Line 125 column 373: end tag for element "a" which is not open.
...;e_reglement_de_la_salle_informatique.jpg</a>.
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Error Line 126 column 35: character "+" is not allowed in the value of attribute "id".
<h3 class="heading-1-1"><a id="Pour+me+contacter" name="Pour+me+contacter">Pour
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Error Line 126 column 60: character "+" is not allowed in the value of attribute "name".
...><a id="Pour+me+contacter" name="Pour+me+contacter">Pour me contacter</a></h.
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Error Line 322 column 58: value of attribute "method" cannot be "POST"; must be one of "get", "post".
<form action="/xwiki/bin/view/Main/WebSearch" method="POST">
The value of the attribute is defined to be one of a list of possible values but in the document it contained something that is not allowed for that type of attribute. For instance, the ?selected? attribute must be either minimized as ?selected? or spelled out in full as ?selected="selected"?; a value like ?selected="true"? is not allowed.
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Error Line 332 column 95: there is no attribute "border".
.../xwiki/skins/default/rss.gif" border="0" alt="RSS" /></a>
You have used the attribute named above in your document, but the document type you are using does not support that attribute for this element. This error is often caused by incorrect use of the "Strict" document type with a document that uses frames (e.g. you must use the "Transitional" document type to get the "target" attribute), or by using vendor proprietary extensions such as "marginheight" (this is usually fixed by using CSS to achieve the desired effect instead).
This error may also result if the element itself is not supported in the document type you are using, as an undefined element will have no supported attributes; in this case, see the element-undefined error message for further information.
How to fix: check the spelling and case of the element and attribute, (Remember XHTML is all lower-case) and/or check that they are both allowed in the chosen document type, and/or use CSS instead of this attribute.