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We report a study of the decay Bs0 → Ds(*)Ds(*) using a data sample corresponding to 1.3 fb-1 of integrated luminosity collected by the D0 experiment in 2002–2006 during run II of the Fermilab Tevatron collider. One Ds(*) meson was partially reconstructed in the decay Ds→ φμν, and the other Ds(*) meson was identified using the decay Ds→ φπ where no attempt was made to distinguish Ds and Ds(*) states. For the branching fraction Br(Bs0 → Ds(*)Ds(*)) we obtain a 90% C.L. range [0.002; 0.080] and central value 0.039-0.017+0.019(stat) -0.015+0.016(syst). This was subsequently used to make the most precise estimate of the width difference ΔΓsCP in the Bs0 - Bs0 system: ΔΓsCP/ Γs = 0.079-0.035+0.038(stat) -0.030+0.031(syst).