If that was the only error in the original CHECKDB output, then no, they weren't masked - as the catalog checks that produce that error are run after the checks that produced the second set of errors.
Holger - was the 8992 error the *only* error in the first set of CHECKDB results? if so, these are new corruptions.
Having it all in German isn't helping things either (no fault of yours Holger!).
Paul Randal
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Blog:www.SQLskills.com/blogs/paul Twitter: @PaulRandal
SQL MVP, Microsoft RD, Contributing Editor of TechNet Magazine
Author of DBCC CHECKDB/repair (and other Storage Engine) code of SQL Server 2005