If someone achieves 2/3 + 1 vote of the total, one has also achieved 2/3 of the total. Hence the usage of the term "2/3 or more" is not necessary in my opinion. However "more than 2/3" means that 2/3 is not sufficient and 2/3 + 1 vote is required. There are different meanings at play here, hence the need for clarification.