@silentguy - your first error should be nothing to do with this plugin, as it has not changed for a long while and with 37,000 users others would have complained about it
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If you give some steps as to exactly what you are doing then we may be able to recommend something. If it is an error on screen paste the exact text in a spoiler, start calibre in debug mode if necessary.
As for the second, it isn't a bug, it is intentional behaviour. So "Kevin Anderson", "Kevin, Anderson", "Anderson, Kevin" and "Anderson Kevin" will all be reported as a match of each other. Yes it means you will get false positives as well but it is trying to weed out the more obscure duplicates with that check.