Tmeple of Chaos Soul Core Bug

I was traversing through the temple of chaos with a friend and got to a soul core room. I went and picked up the last soul core and was told by the game I didn't have it when I tried to place it in its altar. For some reason my friend was able to place to place it instead. The only real problem was the game still considered the soul core on my back. Meaning that I continued to periodically take damage. This persisted through multiple rooms until it finally ended our run.