When Joining Objects

Got something that is stumping me here:
Let's say you have a circle. I want to add another set of verticies to it, like a ring.
No problem, I just put the filled circle in Edit Mode and Add another Circle mesh (not filled of course) at the radius I want it at.
BUT, when I go to Object mode and look at my object, that extra ring is highlighted! There is only one Object however.
I noticed this too way back when working on Zephyr Cove's beach. Joining two sections together left this seam there.
It really affects the textures and vertex painting too.
How do you get rid of this?
Let's say you have a circle. I want to add another set of verticies to it, like a ring.
No problem, I just put the filled circle in Edit Mode and Add another Circle mesh (not filled of course) at the radius I want it at.
BUT, when I go to Object mode and look at my object, that extra ring is highlighted! There is only one Object however.
I noticed this too way back when working on Zephyr Cove's beach. Joining two sections together left this seam there.
It really affects the textures and vertex painting too.
How do you get rid of this?