Big deal? It is pretty big because people can sign up and get access to certain features of the Emulator that they're not meant to. An EXPLOIT is a big deal. (But I also see why they're their is some places).
This isn't an exploit, it's simply a check - not the best check, but you can easily remove it or modify it.
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I'd improve a few things such as your use of threads and how some queries are ran. When you insert a new record you can avoid running another query to get the record by implementing a method to use the LastInsertedId command in MySqlCommand. Also, caching a few things here and there would help ^^
Nonetheless, good job & nice release.