Yes, I know this is common. When I became a christian i went to an mennonite church. And learned their teachings. But my focus never was that they are right in all teachings. But I met a lot of which did it. Later i was in a church which was led from an calvinistic and an mennonite brother. It ends that the calvinistic brother was accused false teaching and was kicked out. He still is my friend, even he is calvinist.