  We study the production and signatures of heavy exotic fermion pairs in the
framework of the vector singlet model (VSM), vector doublet model (VDM) and
fermion-mirror-fermion (FMF) model. We show that the pair production cross
sections are competitive with the ones for the single production of exotic
fermions due to the exchange of a photon in the $s$ channel and to the vector
component of the $Z$ - boson coupling to exotic fermions. We also exhibit some
kinematical distributions.
