We study magnetotransport of a two-dimensional electron system (2DES) in the presence of an additional one-dimensioinal potential modulation. The commensurability oscillations observed in such a density modulated 2DES show a temperature dependent switching of their phase in the case when the modulation pattern is orientated parallel to the current. This behaviour is compared with a recent theory on the consequences of electron electron interaction by Gornyi and Mirlin [Phys. Rev. B69, 45313,(2004)]. The theory predicts a temperature dependent mixing of the components of the resistivity tensor, which explains the phase switching as an overlapping of two kinds of commensurability oscillations. Good qualitative agreement between experiment and theory os found.