"I see someone every day" - meaning you see someone every day. "I see someone every other day" - meaning you see someone one day, not the next, then the day after, but not the next and so on.
What is "I see someone every two days"?
I am sure it means you see someone, have a 2 day break, see them again, then have another 2 day break.
But then I thought, every two days could be one day in between, because every day has no days in between, and 2 comes after 1.
So: What is seeing someone every two days?