Well what I did was search on the UI on a transaction type search an item with an id, then on the code I loaded this search and it gave me the same results, then added another item, on the code, this time it didn't get me any results, if the criteria were overwritten then it should gave me some results, but it didnt, so on the UI, I added the filter twice, so it was ìtem: 1` AND

item:2

and it also didnt give me any results so that's why I say it gets added as an AND