Cal. Rev. & Tax. Code § 3841

If any property, whether subject to a power of sale pursuant to Section 3691 or not, is deeded for taxes to two or more taxing agencies, any one or more of them may sell and convey its or their interest in all or any portion of the property to any one or more of them for any agreed price and terms. Any one of them may, by itself or with another taxing agency, make the purchase.