Did she even know her name ?
Yeah, actually. I just think she's aware that "Pina" isn't really Pina, or she just hates her that much
!!!!!!Spoilers!!!!!!! But also slight correction
She doesn't know that itch!Pina isn't Og!Pina, she finds out after the story ends in an extra Chap.
Even more spoilers for the inpatient (like me)
When Remilia is told Og!Pinas tragic back story by her, the god of the world, and spirits. She desides to take Og!Pinas soul into her so she can be reborn as her eldest son. As practice so when she take Em's soul she can be sure the process is successfully done so Em can be reborn safely.
I don't think I've ever seen Remilia refer to Pina as Pina, it's always been that woman, star maiden, or any other derogatory term.