lookin good man, a few things tho- there hungry ...they shouldnt have yellowing leaves that young. try whipping up an organic feeding schedule or bump the feedings up. they will be stron and full in no time.
lower the lights too that will help strech. what lights you using/
if youve grown many many many times and dont know why your plants are 4 foot tall using flourecents then id start doing some research.
spectrum, intensity and genetics are a few terms that might explain why your plants are doing what they are doing.
and to have more than one plant per container- its fine if you have a big enouch container but to plant alot in one small container is just one small hint that you havent done this before.
buy a growguide and start reading as much about horticulture and propigation as possible...it will help you later down the road. when you understand the process the plant undergoes to become what it is, it will help you have a better mind when it comes to growing them out.
goodluck