Bible Contradiction? Yes or no?

Keturah was Abraham's wife [Gen 25:1]
Keturah was Abraham's concubine [1 Chron 1:32]

Gen 25:1 - "Abraham had taken another wife, whose name was Keturah."

1 Chron 1:32 - "The sons born to Keturah, Abraham’s concubine: Zimran, Jokshan, Medan, Midian, Ishbak and Shuah. The sons of Jokshan: Sheba and Dedan.

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