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No those errors are not normal in any spec epub. It looks like someone who does not know what they are doing, has edited the epub's OPF, removing the package tag unique id attribute or its target and improperly re-used an id.
This can be a sign that the epub was edited using poorly written software or that the epub itself was pirated by someone who feared the unique-id would somehow identify them so they removed it.
Either way, not normal.
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