I would be willing to bet they're not the exact same panel, and if they are, something with the fused display is causing these panels to have some less-than-stellar problems.
And fyi, I noticed the orange/yellow color-cast (especially on whites) at off angles on my retina-display MacBook Pro 13". I seriously think these IPS panels have been downgraded somewhere, intentionally or otherwise.
When i said im not 100% sure i really meant to say im almost certain they are the same panel The yellow tint issue has been present in all the LED and even the LCD iMacs, some some units didn't have it and others did, you have a bad unit as my 27" is perfect and has NO Yellow tinting whatsoever.