Currently, there is no good option to tell a promotion to only apply the discount to two different items.

Example:

Buy item A + 1 of items B-E and get a €250 discount
Buy item A + 2 different items from B-E and get 500 € discount

The first works without any problems.
The second also works, but it also works if you add item B to the shopping cart twice, for example.

There is the rule “Total number of different items in the shopping cart” but this is also counted with items that are not part of the promotion.