Different frequency on APs directed to each other

Motorola advise to use the same frequency channel for APs directed to each other in different clusters. Would the Canopy system work if such APs would operate on different frequency channels?

Are both clusters using a CMM?

We are planning not to use a CMM at the second cluster. And even not to use BHs for the initial period, but to make a remote AP cluster with SM linked to the main cluster.

We 3 AP Clusters with CMMs in one town. Distance of this clusters is approximately 1 mile. Each cluster have exactly same timing. When we tried to use same frequency on APs directed to each other, we had a lot of problems. So we have to choose another frequencies. Have anyone similar experiences?