The "Rose-" name family gets confusing all by itself (starting with the fact that half of them aren't "rose-", but "horse-" in origin), but my spouse's ancestors in northwestern Hungary keep adding Theresia to the mix. I have lists of baptisms with everything the same (parents, address, occupation, godparents) except that the mother is Rosina in seven of them and Theresia in one of them, or vice versa. I also have a case where marriage and other records give the exact name, address, and occupation of Rosina's parents, but the register only has a baptism for Theresia with those parents.
Is there a German diminutive of Rosina and Theresia that could be leading to the repeated name switcheroos? In Hungarian, there's Rozi and Rézi, respectively, but they're fairly distinct, and fail to adequately explain my findings. (These are villages settled in the 1700s by German-speaking Lutherans, but by the mid-1800s, I can't judge which language they used at home.)