Nice! Thanks! I ran this across my database of just over 9500 people. It found 242 cases of double cousins. That seems high, though as I examine the list I find that most of them come from the same dozen or so families. There are lots of Quakers in my background, with some very large and intertwined families.
Run time was about 30 or 40 seconds, which I think is excellent given the processing that has to happen.
Since is looking only at first cousins, an obvious extension would be to look for double second/third/Nth cousins.
I did a quick look for duplicates and did not notice any. Does the code know how to leave out duplicates? Does it know, for example, that “Doe, John & Jones, Fred” is the same match as “Jones, Fred & Doe, John”? Only one of those needs to be reported.
Other suggestions: An option to set the display format of the name. That is present in most other reports so should be easy to add. An option to set how the list is sorted, if it is sorted at all.