Do you have a lot of user sign up attempts? There could be spammers/bots continuously making POST requests to the sign up form, but providing insufficient information to create a client, which would a fraud check to be performed each time without resulting in any orders or new user accounts. I can only speculate as to what actually occurred in your particular case, but I can say that Blesta's order plugin will only attempt to perform fraud checks for new sign ups and when checking out.