831.17  Violation of s. 831.16; second conviction.--Whoever having been convicted of either of the offenses mentioned in the preceding section, is again convicted of either of the same offenses, committed after the former conviction, and whoever is at the same term of the court convicted upon three distinct charges of said offenses, shall be deemed a common utterer of counterfeit coin and punished by imprisonment in the state prison not exceeding 20 years.