The domain that's mimicking your own is apparently hosted at DreamHost and both domains are listed in a DNS lookup as using the same IP. The owner is listed as "United Business Media Group Ltd" (dcntrnoc [AT] ubm-us [DOT] com).
Chances are reasonably high that it is an internal glitch of some description that's caused the problem rather than someone aping your domain purposefully. You should submit a support ticket about this.
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