Quoted from MikeO:Mine has the same parts as yours. Just spacers. And I know for a fact mine are original. The split version works where there is no connection to the art plastic above it. You could use some of those for that purpose on this specific guide plastic but not for all of them.
MikeO - Thanks! So at least now I know I'm not crazy! From what I can tell, Atlantis was the first Gottlieb game that used that clear plastic piece below the upper plastic - to create a lane for the ball. Atlantis was released in January 1975. Top Score/300 (released in August 1975) also had a bagatelle on the right side, but from what I can see in photos of that online, it appears to use the combination of A14487 and A14488 - at least in the spots where there are screws.
El Dorado and Abra Ca Dabra (both 1975) also use the A14487 and A14488 combination, but again, those both have screws going down through the connected parts.
You can't use A14487 or A14488 for Atlantis. The top piece is too short and the bottom piece is too tall - plus there's no way to get the screw and washer onto the bottom piece without cutting of the section that fits into top piece.
I can use the ones I have - they are functional, just yellowed. Frankly, I was more interested in solving the mystery of that piece. I suspect that Gottlieb used those spacers with screws and washers for Atlantis, then discovered a better system - the A14487 and A14488 combination.