I don't think this is the best UX. Consider this escenario:

The user has to select two option. He/she selects Cheese and Tomato (in that order):

What do you want to on your burger?

☑️ Cheese

☑️ Tomato

🔲 Lettuce

🔲 Pickles

🔲 Chili sauce

The user changes his/her mind and decides to take Lettuce instead of Tomato. So he/she selects Lettuce and by doing so Cheese get deselected (because it was the first item the user choose).

What do you want to on your burger?

🔲 Cheese

☑️ Tomato

☑️ Lettuce

🔲 Pickles

🔲 Chili sauce

For me would be more easy to understand if after selecting the amount of items needed all other options get disable status. So first you need to deselect one of the two selected item before to select another.