Why did the girl who played becky on tv show roseanne keep switching back and forth its 2 different girls what was reason

Sarah Chalke played the role whenever Alicia Goranson was not available, and in seasons 6, 7, and 9.
Updated on Wednesday, February 01 2012 at 07:22PM EST
Collections: lecy goransonsarah chalkebeckyroseanneforth