While installing a plain new instance, during the installation process (web gui guided) I receive an error with the extended templating kid:

Magnolia Extended Templating Kit Module (version 1.0.0-rc1)

• Can't copy /modules/standard-templating-kit/config/site to /modules/extended-templating-kit/config/sites/default
• Could not install or update extended-templating-kit module. (Could not execute task: modules/extended-templating-kit/config/sites/default)

(see the attached error.log for stacktrace). I am able to login afterwards, but obv. the extended templating kid is not installed.
Also import and exports of any xml wont work any more and fail.

Taking a look into the tmp xml-files while installing I see the following:

<sv:node xmlns:mix="http://www.jcp.org/jcr/mix/1.0" xmlns:nt="http://www.jcp.org/jcr/nt/1.0"
xmlns:fn_old="http://www.w3.org/2004/10/xpath-functions" xmlns:fn="http://www.w3.org/2005/xpath-functions"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:sv="http://www.jcp.org/jcr/sv/1.0" xmlns:jcrfn="http://www.jcp.org/jcr/xpath-functions/1.0"
xmlns:rep="internal" xmlns:jcr="http://www.jcp.org/jcr/1.0" xmlns:mgnl="http://www.magnolia.info/jcr/mgnl"
sv:name="site" xmlns:mix="http://www.jcp.org/jcr/mix/1.0" xmlns:nt="http://www.jcp.org/jcr/nt/1.0"
xmlns:fn_old="http://www.w3.org/2004/10/xpath-functions" xmlns:fn="http://www.w3.org/2005/xpath-functions"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:sv="http://www.jcp.org/jcr/sv/1.0" xmlns:jcrfn="http://www.jcp.org/jcr/xpath-functions/1.0"
xmlns:rep="internal" xmlns:jcr="http://www.jcp.org/jcr/1.0" xmlns:mgnl="http://www.magnolia.info/jcr/mgnl">

So plenty of double-entries there, which is related to the error.log kindly the source of the error.