Rev. 0 and Rev. 1 boards:
Problem:
- connector LCD2 pinout is mirror-image
Workaround:
- for 2x16 display, wire connections manually, or use a flex cable connected to LCD1 connector instead

Rev. 2 boards:
Problem:
- some versions of 16x2 displays have connector along top edge;  while they can be plugged into connector LCD1, the mounting holes aren't right
Workarounds:
- create your own mounting method (eg. glued spacers)
- or use mounting holes provided with LCD and make connections to LCD2 connector manually or via flex cable