I coined 'dog legs' back when I was making and solving Killer Sudoku. Some Killer Sudoku puzzles will contain cages which span three boxes and these can potentially contain two numbers which are the same. The convention with Killer Sudoku (which I certainly adhere to, but others may not), is that whatever permissable combinations in that cage, no combinations will contain duplicate numbers. These cages look like they 'dog leg' across boxes.
With KenKen and KenDoku 'dog leg' cages are extremely common and are part of the puzzle. Combinations of numbers can potentially contain duplicates and even double duplicates and triplets. Some examples are below.
It is helpful to spot these dog legged cages since the number of combinations you will have to consider will increase and I treat these differently using yellow in the hover over.
the key difference between KenKen and KenDoku is that KenKen only requires unique solutions across the whole row and column - whereas KenDoku is much more like Sudoku - the boxes must also be 1 to n. So in this example of a KenKen puzzle, we have a greater number of chances that a cage of more than two cells will contain combinations with duplicate numbers.
The 4x is a simple one where the duplicates must be placed diagonally from each other. However we don't know if they must be two 2s or two 1s.
The 36x contains combinations with duplicates and one without. It will be the solvers task to decide which is right.
To contrast these, the simple two cell cages such as the 6x highlighted can't contain combinations with duplicates. Therefore the hoever over on the solver is a different colour.
See the article on KenDoku Dog Legs for a distinction between the two types of puzzles.