We search for the semi-inclusive process B0s→D(*)sD(*)s using 2.8 fb−1 of p¯p collisions at √s=1.96 TeV recorded by the D0 detector operating at the Fermilab Tevatron Collider. We observe 26.6±8.4 signal events with a significance above background of 3.2 standard deviations yielding a branching ratio of B(B0s→D(*)sD(*)s)=0.035±0.010(stat.)±0.011(syst.). Under certain theoretical assumptions, these double-charm final states saturate CP-even eigenstates in the B0s decays resulting in a width difference of ΔΓCPs/Γs=0.072±0.021(stat.)±0.022(syst.).Received 13 November 2008DOI:https://doi.org/10.1103/PhysRevLett.102.091801©2009 American Physical Society