You spot a third wheel

You're about to keep right at it, until you suddenly feel a mass of weight under the blanket beside you. From the shape and size it's obvious that this is another Sophie. She unravels herself from under the blankets, revealing this surmation to be true.

Sophie 3: "What the... how did I end up here?"

Sophie 1: "I think it's plain to see that my clone cloned again upon orgasming."

Sophie 2: "That'd explain where I came from."

You distinctly remember waking up to a wet dream in the middle of the night and masturbating so you could sleep. That must have been when Sophie 2 appeared. Though, the specifics of how or why you duplicate don't interest you at all. Your only concern is that now this session has become a threesome.

The newly-created Sophie mixes in with the two of you with ease. You were already on the cusp of an orgasm, and your two clones bring you over the edge in moments. You produce a new clone. You pair up, so that you're having sex with clone 3, and clones 2 and 4 with each other.

Sophie 1: "First pair to cum gets to have the next clone."

Sophie 2: "Deal!"

You decide to cheat by selfishly masturbating vigorously instead of attending to your clone. She thankfully had the same idea so there are no hard feelings, but unfortunately so did your other two clones. All four of you wring out orgasms within the span of a few seconds, unable to tell who was first.

Soon a problem starts to arise, however. As both pairs cum, they produce four additional clones. Math may not be your strong suite but even you've heard of exponential growth. There are eight clones already. Where are you all going to sleep, work and who's going to feed you all?

Sophie 1: "W-wait, girls, you gotta stop! Let's think this over."

Your clones halt their lovemaking for a moment. They too seem to have the realization as you.

Sophie 1: "We gotta try and see if there's a way to reverse this."