In Germany I've two URLs in a parallel use. It's contains an German Umlaut and so both URLs means the same.
The first URL is [Here characters ue in German are written as . The Punycode URL is http://xnferienwohnung-mnsingen-6lc.de/.
By defining a new Website in this case I've to include both URLs for one Side-Name. The URL http://ferienwohnung-muensingen.de is included correctly in the table site and the url is included in site_URL like http://xn%u2014ferienwohnung-mnsingen-6lc.de.
Try using '--' instead of '' in your Punycode url.
Sorry you are right. I've copied the url from a wrong source. It works ...
There's an opportunity here to auto-correct these kinds of typos, and/or provide conversion to/from Punycode.