What is the easiest way to dupe them, disable the slider control (bend controller) on the dupe to be able to modify the dupes start and end and then reenable the slider controls.
Huh? Sorry, you need to be a lot more specific. If there are expressions involved, chances are they need to be adjusted and even outside that it's not really useful if you just assume we would be able to help you based on such vague mutterings. We simply cannot know how your project is structured and rigged, so by all means give us something we can actually work with like a screenshot and a better description of the situation.
That depends on how the wings are setup. I can think of at least a dozen ways to setup flapping wings. We need screenshots that show the modified properties (press uu) of the layers you are working with to give you specifics.
I recently did a project where I created a simple left-wing as a shape layer with a tapered stroke in a 300 X 300 comp that was about 2 seconds long. I used the repeater to generate the right-wing, animated the path that created the wing to make it flap, and set up a 10 keyframe flap cycle with the first and last frames being identical. I made the layer 3D, Then I added the bird comp to the main comp, enabled time remapping, set up a loopOut() expression, and offset the starting times. In just a few minutes I had about 50 birds with flapping wings flying in formation all from one shape layer with a single path.
Give us some workflow details and embed a screenshot using the toolbar and we can probably help you figure it out.
I see you are using Trapcode 3D stroke. In the camera options, there are controls called Z-clip front and back. The workflow is to duplicate your Wings layer, put one copy above the Icon (logo) layer and one above. Name the one above "Front" and the one below the "Back".
Check the back copy, the one underneath for animations and expressions by pressing the U key twice then replace every animation and expression with a simple pickwhip expression pointing to the same properties in the top layer.
Now add this expression to Z-clip Back for the Front layer and Z-clip Front for the Back layer:
cam = thisComp.layer("Camera 1").transform.position; cntr = thisComp.layer("Icon").position; length(cam, cntr)
Here's a simple circle showing some camera moves. The Z Clip splits the 3D stroke so that you can insert another 3D layer between the two halves of the effect.
As long as your wings will bend in the front and back of the center point, this will work. I do it often.
Here's the Project file that shows the workflow.
Wow! Thanks so much!