The error is produced, because of mismatch of the controls/holders in the template and their parent ids. The error is thrown when the parent of one control/holder do not match correct child and docks cannot be arranged properly. We tried to reproduce this on a single template several times with no avail. Could you give us some steps( or send a screencast) that we could follow to replicate the issue here.
All the best,
the Telerik team
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