The “Poll must have different options” error message is displayed if you have added the same option twice in a poll. For example, if your poll had two entries for “Great friend”, the error message would be displayed.
The reason I knew the answer is because I recently helped someone with a similar issue. In that case, we were both confused by the meaning of the error message. I wonder if the error message could be improved to make it more obvious what the cause of the issue is?