In the DR660, you can copy one pattern to another.
In pattern mode select the source pattern, press copy, and the display show the source number and destination number, like this:
106 > 106
Turn the value knob until the desired destination is displayed, like:
106 > 200
Press Enter, the display shows "Sure?", press Enter again to copy the pattern.
These steps should work the same way in the 770.
Mgomes