Experience with seedling mutation? Viable to grow?

You are fine. They look healthy, otherwise. All the times i freaked out about an early ugly plant, they turn out fine. if not, just grow that other one 1-week longer, lol. Even on a mature plant I have one that puts out great buds but has a problem growing the smallest serrated blades on some leaves -- somtimes 6 or 8, or sometimes just 2 fewer blades but only the tiny ones are missing. Occasionally find 2 slightly different colored halves of leaves on it too. Anyway, not the prettiest, but works well with potent bud (the type a heavy smoker requires). I don't think its cotyledoens even fully popped out -- too long ago from seed but something funky i recall then too. But, early on its farily normal for funky-looking seedlings. Maybe not an expectation, but normal enough not to worry.