We had just one at first, and then a week or so later, the second followed.
Our first bottom teeth came a month apart and his first tooth is coming at the top now, only one again! Think it's normal 😊
My 10 month old has 1 tooth thats fully up and a little one coming thru. Its not abnormal like not every child is the same.
My daughters two bottom teeth came in separately 😊 Does seem to be more common that they come together but don't think it's an issue if they don't