During August 2010 a series of solar particle events, originating from the adjacent active regions 11093 and 11099, was observed by the two STEREO as well as by near-Earth spacecraft. For the events occurring on the August 7 and 18 we combine in-situ and remote-sensing observations with predictions from our model of three-dimensional anisotropic particle propagation in order to investigate the physical processes which cause the large angular spreads of the energetic particles during these events. In particular, we address the effects of lateral transport of the electrons in the solar corona as well as due to diffusion perpendicular to the average magnetic field in the interplanetary medium. We also study the influence of two CoronalMass Ejections and associated shock waves on the electron propagation, and a possible longitudinal variation in space of the transport conditions during the above period. For the August 18 event we additionally utilize electron observations from the MESSENGER spacecraft at a distance of 0.31 AU from the Sun for an attempt to separate between radial and longitudinal dependencies in the transport process.