I own approximately 3,000 videos and thousands of hours of old time radio and once in a while, by mistake I sometimes buy a duplicate of what I already have.  I have 25+ duplicates, that I will sell sometime.  Some of my videos are rare.  I own the complete Charlie Chan collection, all 46 movies.  Most people forget that there are 46 not 45 Charlie Chan movies.  One of the Charlie movies is a silent movie and one of them can only be completely understood if one speaks a foreign language (there are subtitles in English).  I have every Dead-End Kid movie ever made and most of all the cliffhanger serials ever made.  I plan on owning everyone available for viewing.  I am working on a catalog of all the movies that I own.  Part of the problem in making a catalog is I keep buying more movies, buying more movies.  Most of the movies that I own are in the public domain.  I have the equipment to edit or copy any movie ever made.  I don't know why I bought it but one of my copiers can copy seven movies at one time and I really don't need it because I don't sell movies.  As of yet I have not even sold one of my duplicate movies.  I will sell them though, sometime.  I sometimes buy  a movie in both DVD & VHS so that I can play with them as to editing (which I am not very good at YET). 
I am 63 semi-retired, not poor, not rich, just comfortable, handicapped and into vit's & minerals & massages for circulation in my legs and feet.  If you don't believe in vit's & minerals & massages you will not live as long as you should!   Because I am diabetic and had a motorcycle accident that crushed my ankle and foot I was told 17 1/2 years ago that I would only be able to keep the repaired foot for an absolute max of  9 - 10 years.  Doctors learn bottom of the cliff medicine, fix it after it has happened rather than prevent it from happening and  for the most part don't understand herbs, vit's, minerals and massages.  By the way the foot an ankle that I was supposed to loose 7 1/2 years ago is pink and healthy, having had over 1,000++ massages on my feet, legs, toes and body (I don't feel that a massage that lasts less than 2 1/2 hours  does a proper job).  I perfer to have at least one massage a week but sometimes I only get one every other week, depending upon how I feel  and if I feel that I need it I get a second massage during the week.   Aloha