Roland SP-404MK Reference Manual page 94

The COPY BANK screen appears.
2
Press the bank [A/F]‒[E/J] buttons to select the bank to copy (source).
3
Turn the [VALUE] knob clockwise to move the cursor.
4
Press the bank [A/F]‒[E/J] buttons to select where to copy the bank (destination).
5
Press the [VALUE] knob or [COPY] button.
All the patterns in the bank are copied to the specified bank.
Performing this operation overwrites (erases) the pattern in the copy destination pad.