Hi,
I’m working on a design for a bakers rack, and came across a strange situation. I have a component that I’m using for the sides of a drawer cabinet, made one, copied and flipped it to get the other side. Later I increased the length and now the copied component is longer than the original. Doesn’t make since to me, hopefully you guys can.
Jim
component problem.skp (32.8 KB)
It looks like the longer one was stretched with scale. Geometry inside the component will change across all instances of a component, but deformations made to the “container” are for the one instance, only.
If you double click on a component, make a change to geometry, you will see all instances change. However, if you select and use scale to resize the component bounding box, that change is only to that selected instance.
Looks to me as if you used the Scale tool on the component to increase the length. You scaled the component not the geometry within. If you’d opened the component for editing, first, selected the geometry and scaled that, you would find that the other instance would have gotten the same changes. The Scale tool usually isn’t appropriate for the sort of change you want to make here, anyway because it also impacts the width of the rabbet which should most like stay the same as it was.
Aaron types faster. 
Somewhere along the way, the component instance on the right has been scaled in the y direction by about 0.89. You can see this using ThomThom’s Transformation inspector, where the 2,2 element of the transformation is ~0.89.
Woo! Hot Topic!
Here is an example…
Thanks everyone, its seems obvious that that is what happened, I don’t remember using scale, (I looked back and it had to happen yesterday - too long ago to remember) and I didn’t know that scale doesn’t effect all components so I learned something new again.