If they ask, just say that you've already done it but didn't get anything from it. When they ask for the emblem tell them you didn't have enough room in your inventory for it so you couldn't pick it up. Granted, you really shouldn't have to lie to people just to do the raid. One of my friends just got Destiny again(took it back before Dark Below), and I already know it might be difficult to find teammates that will help me take him through the raid, but I'll never tell someone that they can't raid with me because they don't have experience. Hell, I prefer to take people through the raid that have never done it, it's just a lot more challenging and fun.