Double CalcuDokus are two partially overlapping CalcuDokus like the following one:

While to generate my Samurai Sudokus I first created separate Sudoku Classics and then merge them, to create the Double CalcuDoku, I developed a program that generates both puzzles to be merged.
This allowed me to create cages that cross the puzzle boundaries.

The overlapping area can cover anything from a single cell to an 8x8 area, although, at least for the time being, my program can only generate puzzles with a square overlap, in which the number of rows and columns is the same.
The example shown above has a 6x6 overlap, although my favourite overlapping actually is 7x7.

If you need custom-made Double CalcuDoku puzzles for any occasion with any size of overlapping, don't hesitate to contact me at the email address that you find on the home page.