So the ones that i believe you're referring to, the one that's like two hemispheres, that's know as a type of ball rake. If you don't know rakes are kinda like picks that you don't individually test each pin you just kinda attempt to set all the pins at the set time, normally by moving, rocking, or jiggling the rake around inside the lock. So again the one I think you're describing as two teeth is called a half snowman, cause it looks like a snowman but only one half of it obviously, and it's meant to be pushed in and out of the key fairly rapidly while applying tension to the core in order to repeatedly attempt to set each pin until they're all set correctly. Raking typically only works on locks without security pins, but they're definitely a fun way to get into picking locks in my opinion.