The credits of the movie They Saved Hitler's Brain can be compared with the original, Madmen of Mandoras. Both are, or have been, available on DVD. In They Saved Hitler's Brain, an additional credit has been added stating "Additional Production by Paragon Productions, Hollywood," whoever they were.
1973 or 1972 is a pretty good guess as to when this new footage was created, based on the fashions and hairstyles. They tried to make it look like 1963, but the budget was just too pitifully low. As to why, the Conventional Wisdom is that the film was part of a syndication film package sold to independent TV stations, but, the original film (Madmen of Mandoras) was just too short for a two-hour time slot (with commercials). So, the film was extended to 92 minutes with new footage. Unfortunately, they spent way too little money on the project, and here we are all these years later making fun of it.