What/who Did My Ex See?

So, this story took place in 2015 or 2016, when I still lived in Portugal.

My ex had found an old laptop that he used when he was younger and spent like a whole week trying to fix it.

One evening I decided to go into the bedroom and just relax on the bed. My ex was sitting on the couch in the living room, but could still see the doorway of the bedroom in the corner of his eye. He was trying to repair the old laptop while I was on my phone. I was facing away from the doorway, so when he sudenlly called out to me and told me what he had seen, it made me kind of uncomfortable.

This is what happend;

- While my ex was working on the old laptop he had seen something in the corner of his eye. He had looked up and seen me standing in the doorway, staring at him. But the thing is, what he saw wasn't me, but something that looked like me. The same face, same hair, same pj.

After just a few seconds, "it" turned around and walked into the bedroom. It was at that moment my ex called out to me.

While all that was happening, I was on the bed, still on my phone, not knowing what my ex was seeing. And I had not seen anything coming into the bedroom. Yes, I was facing away from the doorway, but I was less then one meter away from it, so I would still have seen if somebody walked in.

We were both kind of shocked after that.

Could that have been a doppelganger?

Or could it have been a spirit taking my identity, feeding off of my negative energy to stare hatefully down on my ex becasue of how bad he was actually treating me at times? Becasue I didn't have the courage to do it myself?

I told my mum about it, and she said it could be.

Most of my paranormal experiences happened while I was with my ex and now, soon one year after I left him, nothing has happened to me. I have not seen, felt or heard anything. My mum said it coould have been my guardien angel or her dad, but I don't know.

What do you think?