Dr Lal Bahadur Sharma is accused of acting dishonestly after accepting a two-day contract to work as an on-call medic for NHS Lanarkshire while already contracted to work as a locum doctor at Castle Craig Hospital, West Linton, Peeblesshire.
Dr Sharma had agreed to be on duty at the private drug and alcohol rehabilitation facility from 5pm on December 9, 2005 until 8am on December 12.
However, he also accepted a contract to be on call for NHS Lanarkshire's out-of-hour's centre in Lanark between 8am-1pm on December 10 and 11 that year.
The Medical Practitioners Tribunal Service is investigating the allegation that Dr Sharma's fitness to practise is impaired as a result of his misconduct, and could strip him of his licence.
Dr Sharma is accused of being "dishonest in undertaking to work at the same time for both Castle Craig Hospital and for the OOH service" and for having "caused your wife to call the OOH service at about 8am on 11 December 2005 to report that you were too ill to fulfil your duties".
Dr Sharma, who qualified as a doctor in India, is also accused of failing to provide good clinical care to a male patient, known as Patient A, on December 10. The tribunal will hear claims that Dr Sharma failed to realise the man was over-medicated "despite information within the nursing notes and imparted verbally by nursing staff".
He is also criticised for allegedly failing to get a second opinion or make any arrangements to have the man admitted to a general hospital to undergo treatment for "an overdose or potential overdose".
Dr Sharma is also accused of putting the patient at risk by failing to "instruct the nursing staff as to the importance of undertaking regular, careful observations of the condition of Patient A, so as to ensure that he was not over-medicated".
The hearing continues.