Twin nether towers appear

Nextbook 11 Flex. Local multiplayer server hosted on RCA Tablet. I was on Nextbook when we built a Nether portal. I began glitching back and forth between the two worlds. Suddenly I came back out on the original world side with two large Nether towers right in front of me. However when my partner Thomas left the Nether he could not see them. He could pass through them. I could not. I find this concerning.