Usually, when you have default value set in the web.config it should appear in a textbox you have defined(or another control). The strange is that one of your fields - "Events.Registration_Event" has default value that should be applied. On the other hand "Events.Payment_Amount" does not have defaultValue set, but your control is populated.
Check whether you have applied any default settings in your metafiled controls. If the poblem persists, you could send us your templates to check them locally.
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