Thanks for all the great info and research, everyone! Happy to see someone could make out the last name in the signature, and find a photographer with that name!
So, originally I thought the subjects were my wife's g-g-grandparents. The woman has a family resemblance to my wife's g-grandmother, but I now agree that she is most likely a sister. Here are some names:
Wife's great-great-grandparents who married 4 Nov 1874:
- Johannes Jensson Søre-Hetland (b. 1 Jul 1849, Hå, Rogaland, Norway - d. 22 Aug 1902, Mjølhus, Hå, Rogaland, Norway)
- Martha Malene Andersdatter Veggeberg (b. 17 Oct 1845, Hå, Rogaland, Norway - d.?)
Their daughter (wife's great-grandmother):
- Johanna Mathilde Søre-Hetland (went by Mathilda Hetland in the States) (b. 20 Jan 1887, Mjølhus, Hå, Rogaland, Norway - d. 20 Apr 1970, Hennepin County, Minnesota, USA)
Mathilda's sisters:
- Elen Margreta (b. 1874)
- Martha Malena (b. 1879)
- Engel Maria (b. 1884)
- Josefine (b. 1889)
I will attach some photos of Mathilda. She's the grown woman in the family photo (my wife's grandfather is the boy standing in the front). I think Mathilda is the woman on the left in the other photo, and my guess is the other woman is one of her sisters. This photo has a sticker on the backing board, but I can't seem to find the uncropped scan! I'll look for it when I get home.