Ballarat gallops trainer Archie Alexander and harness racing trainer Paul Rowse are to answer charges at Victorian Racing Tribunal hearings on dates to be set.
Racing Victoria stewards have charged Alexander with having had a horse return a swab that breached allowable cobalt levels.
The Alexander-trained Tom's Knight returned a urine sample containing traces of cobalt in excess of the allowed threshold after the gelding won at Kilmore in November, 2018.
Alexander is facing charges of having administered a prohibited substance and allowed a horse to compete with a banned substance in its system.
Harness Racing Victoria stewards have charged Rowse with having presented If The Mood Suits to race at Melton on March 13 when not free of arsenic - a prohibited substance at a concentration above the allowable threshold.
Australian harness racing rules state a horse shall be presented for a race free of prohibited substances.