We use Magnetospheric Multiscale (MMS) data to investigate the energy dissipation in a magnetopause reconnection electron diffusion region (EDR) event with moderate guide field. The four MMS spacecraft were separated by about 10 km so that comparative study among spacecraft within the EDR can be implemented. Similar magnetic field and electric current properties at each spacecraft indicate the formation of a quasi-homogeneous magnetic and current structure in the diffusion region. However, we find that the energy dissipations detected by each spacecraft are still different due to the temporal or spatial effect of the out-of-plane reconnection electric field (EM) within the dissipation region. Our study suggests that the nonuniform or unsteady energy dissipation in the reconnection EDR may be a universal process.