Oman , UAE , are accepting the duplicating but Qatar and Saudi are NOT.
she can obtain duplicating if she is employed by the same company branch and for very limited positions such as owner or general manager ..etc .. but in your case the story is different ..
she shall come here to Doha by her new issued working visa and after she pass the medical and every required papers and prior to send her passport to paste the resident permit then she has to send her passport to Oman for cancellation other wise due to any fail she will lose both ..