The two choices for this quest, to give King Eldrich the real plans or the fake ones, are mutually exclusive. Once you tell the Queen about it, you have made your choice about which one you are going to do. As soon as you make that choice, the game blocks access to the real plans. The only way of changing your mind is to revert to a saved game dating from before the time you told the Queen about the plot. Similarly, if you tell King Eldrich about the plan to rescue Loren Steel, the real Loren Steel vanishes from his cell, and your party will be unable to find him.
