"More than two buffers in diff mode" - How do you turn off diff on the buffers?

Note the buffer number which you want to put/get the changes by :ls command.

Then prefix your put/get command with the buffer number of your choice, e.g. 2dp.

Source: Vimdiff with multiple buffers.

You should switch off diff mode for the unwanted buffer with :diffoff before quitting it with :q. Depending on your settings (e.g. :set hidden), the buffer will persist in the buffer list (:ls), and Vim will consider it when doing a diff.

A :bufdo diffoff should turn off diff for all existing buffers, though I usually just quit Vim and relaunch it with vimdiff ... should such a situation arise.

This may be kind of late reply but still for future feference

i do

:tabdo diffoff!