I don't know what are you doing in active
CSS style?
Simply do not add the link if condition is not satisfied.
Show link for Pageone.jsp
if you are on Pagetwo.jsp
and vice-verse. Please confirm.
<ul id="Menu">
<c:if test="${param.active eq 'Pagetwo'}">
<li class="active">
<a href="Pageone.jsp">Pageone</a>
</li>
</c:if>
<c:if test="${param.active eq 'Pageone'}">
<li class="active">
<a href="Pagetwo.jsp">Pagetwo</a>
</li>
</c:if>
</ul>
For more samples have a look at Is there an easy way to compare two strings in JSP?