Project IOlcd, lcd controled through a IOexpander(in this case a MCP23016)

duality:
Why does it matter?
isn't it the same hardware?
Or is there something i am not seeing?

It matters if you want your software to be reliable.
It is 'similar' hardware. They attempt to make all of them the same but they are not all identical.
You are not accounting for the variations from one device to the next.

Don

Edit: Bill types faster than I do.