A dipolarization of the background magnetic field was observed during a conjunction of the Magnetospheric Multiscale (MMS) spacecraft and Van Allen Probe B on 22 September 2018. The spacecraft were located in the inner magnetosphere at L~6-7 just before midnight magnetic local time (MLT). The separation between MMS and Probe B was ~1 Re. Gradual dipolarization or an increase of the northward component Bz of the background field occurred on a timescale of minutes. Since both MMS and Probe B measured similar gradual increases, the spatial scale was of the order of the separation between these two. On top of that, there were Bz increases, and a decrease in one case, on a timescale of seconds, accompanied by large electric fields with amplitudes > several tens of mV/m. Spatial scale lengths were of the order of the ion inertial length and the ion gyroradius. The inertial term in the momentum equation and the Hall term in the generalized Ohm’s law were sometimes non-negligible. These small-scale variations are discussed in terms of the ballooning/interchange instability (BICI) and kinetic Alfven waves. It is inferred that physics of multiple scales was involved in the dynamics of this dipolarization event.