Corio used to be a single platform on the east side of the line, when duplication ocurred a new station got built on the west side of the original line to convert it to an island platform.
Lara which use to be a single platform had the new line built around the back of the station to convert it into an island platform. The original single line (which became the east line) got slewed around this new back platform. The new line (which became the west line) got routed into the original platform. As a result when you approach Lara on the up from the West line you see a kink in the track to connect the west line to platform one. A similar thing occured at Laverton (which has since been altered) and possibly also at Paisley ?
This photo from the railgelong website might explain what I'm talking about.
Little River had a new platform 1 built.