Dual employment in India means that the a person is being employed by more than one employer at the same time. It means that while an employer is holding a job and getting full time payment from one job, he is also having additional job in another organisation. There are no specific rule governing the dual employment in India. Factories Act 1948 restricts from any organisation which comes under the definition of factory on double employment in India. It states that no adult worker is allowed to work in a factory when they are already working in another factory. As other organisations are not covered under the factories act, they will have to keep their own restriction.
From the given facts, it is not clear from limited information if you have been in a dual employment, if you are working in another organisation of the same employer. It is not evidently clear to establish a case of dual employement. Major managerial jobs are covered under Shops and Establishment Acts of various states. Even though there is different sections for different rules in these statues, the general outline is the same. In these also there is no restriction per say on dual employment. Unless there is a moonlight agreement, meaning a clause by the employer specifically forbiding you to work for another organisation at the time period you are working there, there should not be any issues related to dual employement.
Reference: Factories Act 1948, Shops and Establishment Acts