-My Fair Lady 60 m *
Hard case. Due to this reason that is explained in the book "The Hollywood Story" of Joel Waldo.
These figures are estimates only and are occasionally revised, years later, as happened with My Fair Lady (WB, 1964), which was reduced from rentals of $32 million to $12 million ten years after it was first released.
But at the end of 1997 Variety published a ranking of all time rental-champs and "My Fair Lady" was with 34 millions. So who was wrong? What is the real number? I don't know. But the trigger to opt for the 30 millions of rentals (as the 2-4 millions more alredy belong to re-issues in 1971 and 1973) has been his career in charts of the season 1964/1965. 15 weeks in number one. And more of 40 weeks in the top 10. Such a career like this supposes a lot more than 26 million tickets (in case there have been 12 millions rentals).
-Mary Poppins 61,72 m *
Maybe it got some more tickets in his initial run. But with the Disney movies is very difficult to reach an exact approximation with so much re-issues. Mary Poppins was the perfect finale for Walt Disney before his death. 5 oscars. And at the end of 1965 was at number 5 in all-time chart (in domestic rentals). And "My Fair Lady" at number 6.
In fact, both films were practically tied in terms of revenue in USA and overseas. But I've always liked "Mary Poppins" more. Let's hope that the sequel is up to the original.