You can (from a legal and kosher POV) always put the same tracks in multiple non-exclusive libraries of any kind. Some RF libraries such as Audiosparx re-title for you by adding a tag to your original title. With others, you should ask if they register tracks with PROs and how they handle titles. Some on-line RF libraries rarely get broadcast TV placements so with those I really don’t concern myself about how the tracks might get registered with PROs.
One thing that many composers do is re-title the tracks ourselves when loading to multiple NE libraries, especially the RF kind whereby they may have no re-title policy. It makes it easier to track things and could *possibly* prevent your tracks from obviously price competing against themselves, should someone do Google searches.
For example, let’s say you have a song in a conventional NE library. If you then want to also put in in a NE RF library, you would re-title it yourself.
HTH