Wis. Stat. § 631.43: Other insurance provisions.

(1) General. When 2 or more policies promise to indemnify an insured against the same loss, no “other insurance” provisions of the policy may reduce the aggregate protection of the insured below the lesser of the actual insured loss suffered by the insured or the total indemnification promised by the policies if there were no “other insurance” provisions. The policies may by their terms define the extent to which each is primary and each excess, but if the policies contain inconsistent terms on that point, the insurers shall be jointly and severally liable to the insured on any coverage where the terms are inconsistent, each to the full amount of coverage it provided. Settlement among the insurers shall not alter any rights of the insured.

(2) Fraud as a defense. Subsection (1) does not affect the right of an insurer to defend against a claim under the policy on the ground of fraudulent misrepresentation.

(3) Exception. Subsection (1) does not affect the rights of insurers to limit, restrict, reduce, or exclude coverage under s. 632.32 (5) (b), (c), or (f) to (j).