2.4 module and antenna
 

hello ppl.i would like to learn a few things about 2.4module and antenna.
i already buy from hobbyking 1 module tx and rx 2.4ghz for my 3pk.
i saw that rx have 2 antennas but 2 antenna dont fit in 1 antenna tube.
does anyone know if need and both antennas to be up or i can just put only 1 antenna and other to hide it somewhere?
is there any problem if i put and both antenna together?

thank you very much for your informations.