Different simout result to the same interface between two block.

I am now study on the demo "Chroma-based lane detection", and I got a question about the different result to same interface in two block. Could someone help me with this.

I put two simout block to watch the value of inport in Lane tracking and outport in Lane Detection, which both are named 'Lane'. However I found the data size of outport is always twice as the data size of inport. Since they all reference to the same interface, I could not understand why this happened. Could someone explain this to me? THX a lot~