we recently purchased a 11 week old male gerbil for our daughter, he was on his own at Pets at home and they said not to put another one with him. My son already ahs a pair of gerbils who are around 6 months old and when we introduced them to each other for about 15 minutes they got on well, with grooming etc. Should we get another male to go with harry our new gerbil or leave him on his own?