The transport properties of Mn doped cuprate oxide La1.85-2xSr0.15+2xCu1-xMnxO4 and Cu doped manganite oxide La0.825Sr0.175Mn1-yCuyO3 are investigated. ln both series, the resistivity for the intermediate doping samples exhibits an anomalous decrease. We argue that in both systems, the Cu-O-Cu pd sigma path and the Mn-O-Mn double exchange path form mutual percolation paths and contribute to the conductivity. The resistivity data for both systems are fitted by using the mutual percolation model. (c) 2005 Elsevier B.V. All rights reserved.