No, paste means the more recent of either "internal paste from clipboard stack" or system clipboard paste as lines (by default) or paragraph optionally.
You are talking about current lyx implementation and I am talking from an user's point of view. From an user's point of view, there is no such thing as internal clipboard or internal paste. There is only one system clipboard and everything should paste from it. The same arguments fit the three LFUN_PASTE case. Bo