I have a late 2015 imac 5K with 16GB of RAM (8GB x 2) installed by Apple. I am planning on buying an extra 16GB of RAM (8GB x 2) from OWC. So 16GB of RAM is made by Apple and the other 16GB of RAM is made by OWC. Is it OK to mix those RAMs from different manufacturers and install them into my imac? They're all 1867MHz.