Double Nether Portal

I went to the nether and spawned in a wall and started suffocating but as i broke out i saw the portal like 5 meters away and it was unlit fo some reason. i had never been to the nether in that world so that was kinda strange. As i made a portal about 800 blocks away and went through i came up exactly where i calculated i would but there were 2 portals. one of them was unlit and i spawned in the lit one. this is a singleplayer world so surely noone has placed another portal or something like that.

//thanks for the free extra obsidian