This is true, but it's really my fault for naming them Susan and Sarah. Yes, the names sound different, but it's easy for people to get names mixed up when they sound and/or are spelled similarly. I, for example, have said Leslie Nielson when I meant Liam Neeson before. That certainly would have made Taken different.
For the record, Susan is (normally) the taller of the two with the long black hair. Sarah is (normally) the shorter one with medium length blonde hair, though I suppose it's sometimes longer. And Susan technically has blonde hair, except she was dying it, and it turned black when her magic awakened.
See? No room for confusion.