Tony, it's hard to give a good answer without reference pictures, but here's a stab at it - the "Oak effect" could well just refer to the outer colour rather than the species of wood, as otherwise they would simply be called "solid oak brackets".
Rather than go to the length of explaining the differences and what might have happened google - solid oak, and look at the pictures - paying particular attention to the grain pattern.
However, whether the grain pattern matches Oak or not, applying more waterbased stain to the cut sections to match the colour of the rest of the brackets, could be a simple solution - but do bear in mind that the colour of the stain used may not be an off the shelf variety - and the Oak stain from one manufacter is often a different shade from a competeing manufacturer.
I hate to say it but if you want an overall matching colour you should return those and buy plain undyed wood; cut and alter as necessary then treat with any stain colour required after that.