[en] Thin self-supporting Cu targets in 11-250 μg/cm² thickness were bombarded with 50-165 MeV Cu sup(qi⁺) ions (7<=qsub(i)<=24) to investigate the target thickness dependence of inner shell vacancy production processes in the symmetric collision of Cu+Cu. Doppler-shifted projectile K X-rays were discriminated from the target K X-rays, and the projectile and target K X-ray yields were separately measrued as a function of target thickness. The K X-ray yields emitted from the projectile and the target Cu atoms are strongly dependent on the projectile initial charge state and target thickness for all the investigated collision systems of Cu sup(qi⁺)+Cu. From the observed K X-ray yields, K-shell vacancy production cross sections averaged over the target thickness t of projectile sigmasub(KV) and target sigmasup(*)sub(KV) were separately derived taking into account the fluorescence yield that can be estimated from the Ksub(α) X-ray energy shift. When the values of sigmasub(KV) and sigmasup(*)sub(KV) are extrapolated to zero foil thickness, the K shell vacancy formed in the collision has been found to be equally shared between projectile and target in a single collision. With the increase of penetration depth, however, the values of sigmasup(*)sub(KV) are greater than those of sigmasub(KV) presumably due to electron transfer of a target K electron to the projectile K vacancy. The evolution process of projectile excited states as a function of target thickness and the resulting variation of projectile and target K X-ray emissions are discussed. (orig.)