New to this game, just picked up a car and stripped the rear suspension, the trailing arm ends are elongated in a sort of oval shape is this common? I’m going to replace them and the bushes but wonder why this would happen?

Can you post some photos to show us exactly what you're talking about?

If I understand your description it sounds like the ends have become stretched - are the bushes a tight or sloppy fit in the ends?

If they're a sloppy fit then then ends must have stretched and that would indicate to me the ends need to be made of thicker walled tube to resist stretching/deformation.

Some photos will definitely show us what's gone / going on.

Is every bush housing elongated? I could imagine one or two getting stretched from e.g. hitting a rear wheel on something solid.