Andrias killed a child because the Amphibia CORE is a bitch and wanted her as a host(*Cough* Darcy *Cough*) and regretted it because he formed a bond with said child
Asgore killed six children to free the monsters, regretted it because he didn't want to and deep down, wanted to raise them himself.
Both are similar in many ways, but different in many ways too.
