Ok, I'm a rookie, so don't flame me
I just started doing tandems, and have only done it on one outing, but my buddy showed this way to me and it seems to work ok.
tie on 1.5 feet of tippet, slide your indicator fly onto the tippet, the knot between tippet and leader will not let it slide up the leader, slide the indicator fly on (threading through the top of the fly so it rides right side up on the water. About four to six inches below the indicator fly, tie another knot in the tippet to keep the indicator fly from sliding down the tippet. This give 3 to 6 inches of play in the tippet for the indicator fly to slide up and down the tippet. At the end of the tippet, tie on your dropper fly.
I am told that this allows the indicator to move more freely and naturally, though I am not experienced enough to be able to tell if this is true or not.
I have not, nor have I seen anyone catch a fish on the indicator fly, so I don't know if the leader keeps them from doing so, in essence acting like a strike indicator more then a second fly, or what would happen if a big fish hit the indicator. My suspicion is it would pull the indicator down the tippet if the knot were not big enough to stop it.
I have had the thought that if the fish are tippet shy, maybe you could tie on a longer tippet, knot it a foot or so away from the leader, slide on the fly, knot a few inches below the indicator, and then tie the dropper on at the end of the tippet.