This works with other growing methods to, anywhere you've started more than one seed. Normal practice is to clip the extras, saving the best looking sprout. If you catch it early enough, you can often extract the extras and transplant them to somewhere else. This works best when the roots are not well established yet.
https://youtu.be/Z9oPf1Fhoxk
https://youtu.be/Z9oPf1Fhoxk