MPC 2500 - Input Thru - Confusion

MODE
You can select the input signal, ST (Stereo), L (L channel) or R (Right channel).
Please choose LR to use L and R by a separate set.

what does the mode

L
R

do?

is that a L+R summed together?

bottom left hand corner in the pic

Each input is treated independently. Should be obvious what that mode does from the screenshot... Summing the inputs is one option.

the part that causes confusion is when i have stereo selected my l/r channels peak independent from one another. yet when i use the bottom option LR, they both peak the same, as if they are just summed together.

EDIT:

L R mode is summing the L+R channels (not sure if this is the correct term)

when playing a record with the drums panned to the left and the vocals panned to the right

in L R mode it outputs the incoming signal as L + R, you do not get the drums on the left and vocals on the right

in stereo mode you retain the panning of sounds drums on the left chan and vocals on the right

Try filtering one of the channels or sending one channel to an effect or different output. They are summed (with all other sounds) at the output. Before they get all the way to the output they are treated as two separate signals. Regardless of meters.