They were found guilty by a court yesterday in the northeastern town of Nelspruit of entering the park without authorisation, killing and dehorning the two rhinos and illegally carrying a firearm.
They were arrested in May 2012 during a joint operation involving the South African national parks' special investigation unit, rangers, police and the army.
South Africa is home to about three-quarters of the world's rhino population. Poaching gangs target the horns which fetch thousands of dollars on the Asian black market, where they are falsely believed to have medicinal properties.
The worst affected area of the country is the vast Kruger national park which borders Mozambique, which is used as a rear base by poachers who are increasingly well equipped, armed and organised.
The South African authorities have recently announced plans to re-erect the electric fence that once prevented infiltrations by anti-apartheid militants.