I guess another possibility (given the age gap between Angelina and Adelaide) is that Angelina was born before Sophia's marriage to Frederick Mower, and so she would have been christened using Sophia's maiden name, or if from a previous marriage then that man's surname.
Did the person look just for Angelina Mower or are you confident they would have spotted any Angelina anythings?
(this thread is getting quite confusing as I see the title has changed and more added to the origiinal request - so the reading of it through does not quite follow!)