Can more than one ‘Umrah be performed on a single trip, and what is the required waiting period between the two ‘Umrahs?

There is no harm in repeating Umrah, and Islamic law has not specified a particular time between two Umrahs, as it has been reported that the Prophet, peace and blessings be upon him, said: "Umrah to Umrah is an expiation for what is between them." Aisha, may Allah be pleased with her, performed Umrah twice in less than twenty days. Some scholars held the view that the period between two Umrahs should be long enough for the hair on the head to grow sufficiently for shaving, which is about a week or ten days.