A Detroit woman is demanding answers after her mother's casket was opened and another woman was lying inside it -- because someone had apparently created her own mom.

Here's the deal ... Kimberley Moore recently passed away in Michigan, and her family -- including her daughter Bianca -- was handling funeral arrangements according to detailed instructions Kimberley left behind.

During the process, Bianca went to the Hutchinson Funeral Home in Detroit to see her body before the official viewing ... and she realized the person in the casket wasn't her mom -- though it wasn't her face that tipped her off, she said.

Bianca told Fox 10 News in Detroit ... "I looked at her feet, and I didn’t see that mole that my mom has on her feet, and I looked at that man and I said, 'Sir, this is not my mama,' and he said it just like this. He said, ‘I’m sorry. They must have cremated your mom a week or two ago. I’m so sorry.'"

She says she and her family are trying to figure out where her mother's ashes might be now ... and she also wants the body to be identified, so the other woman's actual family can pay their respects.

Hutchinson Funeral Home shared a statement regarding the mix-up: “We are heartbroken and deeply sorry for what Ms. Moore’s family has experienced. We have launched our own internal review to determine exactly what happened, and we will deal with it accordingly.”

Everybody makes mistakes ... but that's not going to bring Kimberley's family much comfort.