There's a few possibilities. 1) Your mother gave the small globe to you to spite you (as you say she's not above doing that), 2) She absolutely adores the globe herself, and gave the small globe to you hoping to placate you, 3) One of these other scenarios such as keeping the large globe to spite your father and giving the small globe as a token. I guess my money is on #1 since you say she likes to play mind games and expressed that she wouldn't leave it to you as an inheritance.