Imagine the situation: You are an active member of a congregation of Jehovah's Witnesses possibly born into the organization yet something is different about you. There is an overwhelming desire for members of the same sex. Somehow you are able to experiment with another person you are attracted to and find the sexual activity very satisfying. Of course you know or learn that the sexual acts that you participate in are wrong, but it is your little secret. perhaps you think " If I go through the motions of being a witness around the friends in the hall, I can continue to do my thing when they are not around". This reflects an attitude that god does not really care about humans now or that the good works can cancel out the bad ones. This is the double standard of a " double life" - a witness around witnesses but a worldling around unbelievers.
The double life can take many forms. A person can simply be worldly all the time with the exception of the time spent in church- this is so very common today. On the other end the person can be completely devoted to god with the exception of a few minutes (or longer) spent fulfilling illicit sexual desire. Sometimes this could take the form of sexual encounters with one very special person only. Of course a double life is most often led by heterosexual men, but this could apply to women and of course, to homosexuals. How far it goes depends on each individuals conscience