Negative and positive

I took a test on christmas <a href="">eve</a> and got a negative (night pee) even hours later stayed negative. Yesterday i took another test it was a 2 pack so same brand same box and got a faint positive (morning per) idk witch to trust people are saying the positive was invaild but idk! I dont want to get my hopes up and i dont want to test again so soon. Witch should i trust?