Given how shitty his summoning is, why on earth would he try his hand at that again? Raising her age by 5 would make her have more muscle and get over the limitation of her being useless due to being a toddler, basically.
He already opened the door to gacha, that's why he summoned another. He's hit the mindset where you keep trying because any time now RNGesus will have mercy on you.
He could have chosen +5 age OR +2 attack BUT he's got sh*tty decision making or is actually subconsciously addicted to taking care of children that he DECIDED FOR ANOTHER ONE TO FEED.