Were they oily when you found them (oily like gear cables)?
Is there any chafing/polishing on the inside/outside, in axial/radial directions?
Have you ever changed the gear cables in the past?
Maybe they have been used to add length to the outers?
Assuming that you were running V's, maybe they have something to do with the noodles (may explane why there are two)?
I've found noodles with plastic liners and loose ferrels that fall appart when dismantling.
Do your shifters still operate ok? I can imagine it as being a guide from in there. (Again, a pair would match up)