He is talking about ghosting. Try removing your filter and you will probably see that reflected image disappear.
It is caused when light enters your camera through the lens, hits the sensor, but some of it reflects off the sensor onto the filter and back onto the sensor, thus causing a 'ghost' image. Because the filter is directly parallel to the sensor, the filter is often the most likely cause of ghosting.
Yaya..

Ok noted. This week will go and try again.
Thanks la everyone for all 指教。。。
