The current repartition inside a HTS cable is very important for determining its AC losses and can be influenced by the uniformity of several parameters, either linked to the physical properties of the individual tapes (critical current Ic and power index n) or due to the manufacturing process (contact resistance). This work investigates the importance of the non-uniformity of these parameters for a manufactured 16-tape straight superconducting cable by means of finite element method (FEM) simulations. The utilized non-linear E-J model includes the anisotropic dependence of the critical current density and the power index on the local magnetic field. It is shown that the non-uniformity of the cable parameters influences the behaviour of the individual tapes, but not that of the whole cable. The utilized FEM model has been validated by a comparison with electrical measurements of the cable AC losses, as well as with the results of another simpler numerical model, which considers the cable from the macroscopic point of view.