Objectives with a criteria type for using something only increase when you're holding two ore more of the item/block while using them.

How to reproduce:

Create an objective e.g.: /scoreboard objectives add Test minecraft.used:zombie_pigman_spawn_egg

Hold only a single spawn egg and use it -> Nothing happens

Hold at least 2 spawn eggs and use it -> It increases

This can also be reproduced with blocks:

E.g. scoreboard objectives add tsTest2 minecraft.used:dirt

Only holding a single dirt block while placing doesn't increase the score. Holding multiple ones increases the score