Infinite carousel of 18 things or 4 carousels of 6 things

For a table interactive, I have a menu of 18 things presented in a carousel. Those 18 items are divided into four categories. The carousel will move by swiping either side, and the menu on top will highlight the category that it belongs. The 18 things are organized alphabetically. If the user taps on a category, the carousel will go to the beginning of that category. But the behavior of the menu changes, because if the user taps in the category that they are, nothing happens, because they are already in that category. What is a better UX behavior? Leave the 18 in one big carousel or create a carousel for each category and only when the user taps in a different category the carousel will show that new carousel.