I have to stand up for the OP:
"Kindle 5" is used by resellers as a marketing name for Kindle NT black here in the Czech rep. as well.
Their naming scheme is probably based on
Wikipedia although they diverged in case of KT2: they call it "Kindle 6 Touch" while the Wikipedia article calls it "Kindle 7".
The scheme actually counts the basic models while keeping the "special" models out of the numerical sequence.
I.e. Kindle 1, Kindle 2, Kindle 3 (=Keyboard), Kindle 4 (=NT 2011/silver), Kindle 5 (=NT 2012/black), Kindle 6 (=KT2).
All this mess is caused by Amazon's failure to introduce a stable standard for naming Kindle devices.