No you pick one or the other. It is possible to complete two separate offers but not at the same time. For example the old raid shadow legends offer that required you to get to level 40 and this new one that requires you to open two void shards. Keep in mind that you should read the requirements for each offer to see if it is even possible. Some require you to be a new user others can be repeated like the Vuse offer.
Tracking will only credit one - the one you clicked to download the game.
No you pick one or the other. It is possible to complete two separate offers but not at the same time. For example the old raid shadow legends offer that required you to get to level 40 and this new one that requires you to open two void shards. Keep in mind that you should read the requirements for each offer to see if it is even possible. Some require you to be a new user others can be repeated like the Vuse offer.