Please explain this about seals

They are separate seals with the same effect, allowing you to have 2 teammembers with a +atk/def/res/spd or HP effect. So, example, you have Nowi and Fae, and you want them both to use an atk+3 seal. Well, obviously each seal can only be equipped to one characters. With the Squad Ace seal, you have 2 separate Atk + 3 seals, so each of your mighty dragons can have one.

None,they are just there so you can get 2 +3 atk seal in a team,for example.

Bragging rights?
There is no differente, tbh.