Thanks I wasn't sure what this was talking about at first, but I remember talking about it before under different names.
If I understand correctly, this is about how pre-tribbers believe that when a third temple is built that animal sacrifices will be reinstated. However, being unable to make the desired "memorial nature of the sacrifices" mesh with Ezekiel 40-48, they needed to invent dual covenant theology which allows two covenants to exist side by side. The old covenant, they say, is not obsolete and applies to Jews and the new covenant applies to Christians.