Invariant probability measures can be studied through their projections. In particular, the study of barycenters of these invariant measures has received much attention in resent years. K.C.Chen and X.Dong (2010 [3]) found a way to construct different orbits with the same barycenter for the tent map. It can be seen as that many invariant measures have overlapped projection along the direction f(x) = x. This motivates us to consider: when can invariant measures corresponding to two distinct transformations have overlapped projection along some direction? This thesis aims to discuss this problem.