I saw myself step out of the door of the machine, stab myself in the back of the neck with a penknife, then drop the knife and sprint out of the room.
My duplicate hadn't even had time to finish whatever warning he was giving me. He'd gotten as far as "There's no time. The machine is dangerous. You've got to–" when a third me came out, murdered the other me, and fled. What could I do? I ran out the door, chasing the third me.
I'd barely gotten around the corner outside when I felt the barrel of a gun jammed roughly against the back of my head. A voice distorted by exertion told me to stay still. An unseen hand pressed a bloody penknife into mine. "You can't let him answer any questions," he told me. "You'll understand soon enough. You know what to do at this point."
The gun pressed into my head a little harder, and the hand shoved me forward. Hidden next to the dumpster was the machine, looking a little worse for wear. The door hung open. I tried to turn my head to get a look at my adversary, but he pushed me a little harder and I fell into the door.
There was a brief sensation of floating, then I stumbled out the door again. I was back in the lab; I could see myself, staring incredulously at a better-dressed version of me. The well-dressed me had his back to me. He was saying, "There's no time. The machine is dangerous. You've got to–"
Crazy as it sounds, the impulse hit before I could question it. I jammed the bloody penknife into the back of my duplicate's neck. I had to come in at an angle, turning it from a stab into a narrow slash. Skin and muscle parted under the blade, and blood gushed from the wound, covering the knife and my hand. As my copy collapsed to the floor, and my younger self started to stand, I sprinted out the door.