Can people be between 2 religions at once?

Sort of. Unlike Western religions, Eastern religions are not mutually exclusive and individuals can be Buddhist, Shinto etc. at the same time. Even in the West, attempts to convert various groups often led to branches of the older religion being incorporated into the newer one. For example, Christmas was originally a pagan holiday and many of the pagan trappings, such as Christmas trees, became incorporated into the Christian holiday. In countries with freedom of religion, such as the USA, individuals are free to practice whichever religion or combination of religions they wish, even if what they practice is not theologically sound from the perspective of the mainstream doctrine of these religions.