As one of the elder members of this forum might I suggest you get them both together, perhaps ask them for a drink at your place to help relax them, explain what has happened and I am sure you can all laugh about it and see it for the innocent mistake it was. If they are so identical I am sure it is not the first time something like that has happened. Once you have sorted the matter, and everyone is friends again,suggest that to avoid a repetition of the unfortunate incident they both take their clothes off so you can check them for anything that would help you identify them correctly in the future. If you are having difficulty doing this once they are undressed I am sure the other forum members would be willing to assist if you post photographs, or video, of the young ladies in question. As always happy to help.
There's an idea for the summer before the season starts again...an agony column. Any problems send them to "Uncle Garlic's Agony Page...your problem solved and the p**s taken regardless of race, colour or religion."