1. If I look at the TomTom POIs, say for Europe, there are two files for most countries. One Legacy and one Premium. The Premium file for any given country is always larger than the Legacy one. Also, when I use both files, there are double entries for many places (e.g. when I search for a restaurant). Taking the above two facts into consideration, I tend to conclude that for TomTom POIs, all Legacy places are included in the Premium. So it should be enough to use only the Premium files, since by putting on top the Legacy ones, I will just get some double entries.
2. For Navteq POIs it looks to me it is different. For most countries there is a "standard" (no particular name for it) file, and an extended one. When using both for a given country, I sometimes get a double entry when searching for a POI, but not so many as in the TomTom case. Moreover, the extended files for many countries are smaller than the standard ones. So there must be places which exist only in one of the two files. Thus, in contrast to the TomTom POIs in my point 1 above, it looks to me one should use both files in the case of Navteq.
Is the above correct? I guess this must be explained somewhere on the web, but I could not find any relevant information.