I'm really stuck on a XPpath problem that should be fairly simple (I
think): I need to check if an element that got a unique local-name()
among it's siblings. And, I have no way of actually knowing the
local-name() when I generate the XPath.

For example:
<root>
    <a />
    <b />
    <b />
    <c />
    <c />
    <d />
</root>

a and d should pass, the b's and c's shouldn't

To check if element name is unique you can just count elements with such name:
<xsl:if test="count(/root/*[local-name()=$name])>1">
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Oleg Tkachenko
Multiconn Technologies, Israel