I believe the diagnoses of the three leaf seedling is called a "whorled phyllotaxy" which is a kind of genetic anomaly, but it's nothing to worry about. I think it'll grow out of it, but if not, it should still grow normally. As for the stretched seedling, it could be a number of things. Temperature variations and nutrient deficiencies can cause a seedling to stretch, as well as low levels of light. Are the leggy seedlings under direct sunlight? Or are they slightly shaded throughout the day?