My sister's name is Kallie which, in her case, is used as the diminutive of Kathleen. It has historically been used in my family. My great aunt was also Kallie when she was younger but changed that to Kay as she grew older since Kallie was considered juvenile. This side of my family is as close as three generations originating in Ireland.
Kallie Flynn Childress is an American actress. She is best known for her role as Yancy in the 2004 film Sleepover, for which she won a Young Artist Award for Best Performance in a Feature Film - Supporting Young Actress at the 2005 ceremony.
The only Kallie/Callie I know spells her name Kallie, and is named Kalmia. The c just looks weird, and I honestly think it's weird for Callie to be short for any other name. I wish Kalmia was more common, with this as a nickname.