IFPS stands for the Integrated Initial Flight Plan Service, and all IFR/GAT flights within the IFPZ (IFPS Zone - area covered by IFPS; basically the whole of Europe, full details on the Eurocontrol website). Due to this, IFPS is split into two units, one in Haren in Brussels, the other just south of Paris in Bretigny, to act as backuo for each other in the event of a critical failure of a unit. To keep both units functioning, there is a roughly equal split of messages, which is determined by aerodrome of departure. Essentially, IFPU1 (FP1; Brussels) deals with all flights departing the northern half of Europe, plus anything coming into the IFPZ from North and South America, while IFPU2 (FP2; Paris) deals with all southern European deaprtures, plus everything other than the Americas coming into the IFPZ.
Don't know who's claiming they're at Aachen or Britanny, but I suspect it may be misunderstood accents (Haren and Bretigny)
Clear as mud!
edited for spulling