Here is the list of Mortgage Lifter tomatoes from the pre-eminent tomato knowledge source, Tatiana's Tomatobase. How close they are to each other I do not know. Like Cherokee and Brandywine several may be hooking on to a popular name rather than being similar or another version. Personally I have grown Mortgage Lifter, Estler's and Radiator Charlie's. I am not sure I can tell the difference since they were all in different years under different conditions.
Mortgage Lifter
Mortgage Lifter Bicolor
Mortgage Lifter, Carter's
Mortgage Lifter, Estler's
Mortgage Lifter, German
Mortgage Lifter, Halladay's
Mortgage Lifter, Mullen's
Mortgage Lifter, O'Driscoll's
Mortgage Lifter, Pesta
Mortgage Lifter, Quisenberry's
Mortgage Lifter, Radiator Charlie's
Mortgage Lifter, Red
Mortgage Lifter, Rieger's
Mortgage Lifter, Watson's
Mortgage Lifter, Yellow