Their shapes are so similar I think they work together. You will need to spread those two colors to other parts of the room. For instance, put the brown bolsters on the blue sofa and buy some dark blue pillows for the brown sofa. Look for a larger rug with both of the sofa colors, and get a chair that matches the brown sofa to sit opposite it. Put some dark blue art over the brown sofa. That should allow all the pieces to belong to each other.