Help getting a consistent stain across different types of wood
This will still take some experimentation.

Plywood will always take the stain harder than solid wood. If you are using conditioner on the plywood only, that is a good start. You will definitely need to sand the plywood over the original, in one direction. The sanding from the producer is too coarse and will make the stain take darker besides the dryness of the veneer from the laminating process.

Start with 120G and do a sample with the conditioner and maybe that will do it, A finer grit, up to 220, maybe what you need to go to. be sure to sand with the grain. 

A tip to insure complete sanding is lightly mark the top with a pencil and sand until the marks are gone, that will have the same scratch pattern everywhere. progerss your sanding with 100g 150g, then 220g