The Murders of Molly Southbourne
Molly lives with her loving but tough parents on a farm in the present day. There is one rule: If you bleed: blot, burn, and bleach. Okay, that's weird. There's a reason for the rule--Molly's blood generates clones of herself at her current age. Some of these appear harmless, but most become violent. Her parents have to kill and dispose of these Mollys. And when Molly eventually has to make her way in the world alone, she has to learn if she is human or not.
This is a novella and a fantastic tale of horror.