My wife chose her burger first and ticked the boxes to say what toppings she didn't want. It asked more than once, but because she'd already told them she didn't bother repeating herself.
The same thing happened to me but I did bother repeating myself, just to see what would happen.
This is what happened:
On the left, the multiple boxes from the Deliveroo web site. In the middle, the order summary on the web site. On the right, the printed receipt that came with the order.
I felt satisfied that my efforts had served to waste some of their actual ink.
The burgers were pretty good, as it happened, and neither of them had any toppings we'd asked to be removed.
Next time, I think I'll add the house sauce to the list, though.