I noticed the distance between them. Is it possible that you put two seeds in there by accident? Do you re-use soil? Especially soil that had a seed or two that failed to germinate in it? Both of those have happened to other growers on here, though I don't remember the threads that had the posts in them.
I have separated seedlings, and it's best to do it asap if you're going to. The longer you wait the more roots they put out, and the higher the risk of damaging them. Some guys wait a while to see how they're growing and then cull the weaker one (assuming there is a weaker one). It's not hard, you just have to be gentle. I got my gf to do it once, she had a lighter touch. Take a plug of soil around the seedling, pull it out and put it in a new pot, then fill the hole left over with some new soil. Easy.
You could also start a new thread asking for advice on how to do it, or search for threads about it.
