Why is the object on the right being selected when I select the object on the left?

I need to understand the reason of a specific behaviour. I'm in Object mode and when I select one feather on the left wing, automatically the corresponding feather on the right wing lights up, BUT I have no Mirror modifier, no X mirror, no Topology mirror activated. Do you know if there are others reason that explain this behaviour?

Check the attached video below:

attached video

• it would be helpful if you would add screenshots to your post, and upload a copy of your ~.blend file to <blend-exchange.giantcowfilms.com> or a similar site, and edit a link to the file into your answer. – brasshat Sep 28 '16 at 22:34
• Should they be two distinct objects? At first sight, looks like you have applied the mirror modifier. – Carlo Sep 28 '16 at 22:39
• Yep, it looks like they are not two objects at all – Duarte Farrajota Ramos Sep 29 '16 at 1:02
• You could try checking both the highlited and the selected objects in the 'Outliner' panel, see if they are linked. I've cured a few problems this way. – Edgel3D Sep 29 '16 at 3:29

1 Answer

At the very beginning of your movie, while you're still in Edit Mode you can see that both feathers are actually one object with two unconnected mesh parts.

When you select one of the feathers, the other one is highlited as well because it is the same object.