The 8200-CHS has the capability of detecting up to 4 simultaneous layers but certain types of standard messages display only 3 layers .

If the lowest layer is optically dense,  the returns from beyond the first  layer are extinguished ,  and the layers above it are not detected until a gap in the lower layer is detected.   If the cloud is not optically dense,  the return from a higher level cloud is not significantly attenuated when passing back through the lower layer,  so both layers can be detected.

Here is a case where multiple layers are  at 6620 and 7290 are both detected.