Matching family tree profiles for N.N.
It is Eyrbyggja Saga that says that Olaf the White was the son of Ingjald and Thora, the daughter of "Sigurd Snake-in-the-Eye". So perhaps she was married twice, but the Saga does not mention any other husband.
It is assumed that other sources that show her married to Olaf Gerstead-Alf Gudrodson, King of Norway, is incorrect. This Olaf is the grandfather of the Ingjald that married Thora.