We study the indication of large different branching ratios between B−→D(∗)0K−K0 and Bˉd→D(∗)+K−K0 observed by Belle. Interestingly, the same situation is not found in the decays B→D(∗)K−K∗0. If there exist no intermediate resonances in the decays B−→D(∗)0K−K0, a puzzle will be arisen. We find that the color-suppressed processes B−→D(∗)0a0−(1450) with a0−(1450)→K−K0 could be one of the candidates to enhance the BRs of B−→D(∗)0K−K0. Our conjecture can be examined by the Dalitz plot technique and the analysis of angular dependence on K−K0 state at B factories.