test vectors for 3DES seem to in fact be testing DES - not 3DES
It is for the 1st version of 3DES which is only using the same key three times (3DES-EDE1)

Which is equivalent to DES (I think they did that so you could use 3DES to exchange with someone using DES).

There are 3 different versions (or ways of using DES). EDE3 is the strongest with 3 different keys being used.