EM8617 Can my neighbors and I both use an EM8617 or can this cause problems?

It is no problem to use both an EM8617 (also for the EM8605 / EM8610 / EM8615).

Please note that if you are learning the alarm system, there is actually no movement with your neighbors or the alarm system of your neighbors is temporarily disabled. Otherwise, the sensors of the neighbors can be detected first by your EM8617 instead of having your own sensors configured.