In addition to their shear-thinning behavior, polymer melts are characterized by first and second normal stress differences, which are responsible for the occurrence of secondary motions. Viscoelastic flows through straight ducts exhibit secondary motions which cannot be explained solely by the first normal stress difference. These motion originate from the combination of second normal stress difference and non-circular geometry. In polymer coextrusion processes viscoelastic two-phase flows are involved and influence the layer formation. Using polymer melts with different pigmentation the layers deformed under the action of second normal stress differences become visible. The materials were extruded separately and after the screws, they were merged in a feedblock at a well-controlled ratio. The interface is almost horizontal when the material enters the die channel and is deformed during layer formation towards the channel exit. In this work a new solver for the OpenFOAM CFD toolbox is used, which handles viscoelastic two-phase flows. A derivative of the volume-of-fluid (VOF) methodology is used to describe the interface. A simulation of viscous flow using the Carreau-Yasuda constitutive equation produced results which deviated from our experimental findings. Different types of polymer melts such as polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET) are used in this study. In a coextrusion process usually the less viscous phase tends to encapsulate the more viscous one. However, the different viscoelastic properties of the melts also influences the interface deformation. The materials are characterized by small-amplitude oscillatory-shear rheometry and a multimode Giesekus model is used for fitting shear viscosity, storage and loss modulus. In our simulations, interfacial tension was also taken into account. The experimental observations and their numerical counterparts were found to be in good accordance.