Pregnancy test negative then turns positive

Has any ladies ever taken a test, and it be negative, then go back to check it again and its positive...I read up on it and seems like it happens very often. Some are even saying that they now recommend keeping all hpt, as they could change after recommended time of 10 minutes. How many here has that happen to?? And was it really a BFP??? Did you go on yo have healthy babies?? Please, I know we all here aren't experts, just need people who has experienced this!!! Thanks!!!