A few days ago, I had a really weird experience.
I was going out with my sister and we were getting ready. I saw her sitting at the computer. I'm not sure if she was doing anything, but she was definitely sitting there. Obviously this was strange, since we were going out and I encouraged her to hurry up. When she didn't respond, I assumed she was engrossed in something. Then I went upstairs... And she passed me on the stairs! She was wearing a dress, which the other sister wasn't. I just stared at her. I told her that I had just seen her in the back room. So we both looked at the computer, and sure enough, she was sitting there. My sister spoke to her other self and it turned to the sound of her voice. It didn't say anything and then turned back to the computer.
We were freaked and then ran out the front door. I got in the car and as we reversed round the corner, the other sister could be seen, still sitting there. I drove to a shop just to sit in the car park and reflect on everything we had just seen. My sister said it was wearing clothes that she had thrown out the day before, which we both think is quite weird. After an hour of discussing and trying to debunk what we'd seen, I drove back to the house.
Driving round slowly, I looked in the window, and to my relief, there was no one there. Taking advantage of the absence of the other sister, we ran in, grabbed our stuff and turned all the lights off. We then went to our parents and I haven't been back since. Our parents assume we are both making it up to get free board in their house.
She swims in the River Colne. I was worried that it might not be legal to swim there, but it is and so I can tell you.