Formation of spatial cavity solitons upon degenerate two-wave mixing in interferometers with Kerr-like nonlinearity has been investigated by means of theoretical and numerical modelling. The process of spatial solitons formation is discussed from investigation of properties of domain walls connecting different intensity levels in the light beams transverse profiles. It has been shown that the spectrum of coupled bright and dark cavity solitons has a zone structure and the transitions between different levels have been studied by means of stability analysis and numerical modelling. An analytical model describing the properties of domain walls connecting different homogeneous solutions were developed based on parametrically driven Ginsburg-Landau equation for complex order parameter. Numerical modelling of multistable bright and dark cavity soliton excitations and their metastable clusters is also performed.