The fault, dear Ardy, lies not in your SEs, but in your eyes ...
-- Brock Shakesbeer
You said this happens when you focus close on bird feeders and then look far away at the trailer, or when you look at the trailer through the trees.
The same thing happens to me in similar situations on occasion so I think I know what's going on here.
This optical illusion can happen when your focus accommodation starts to wane, but I've even experienced it when I was a teen.
In both the cases you mentioned, your brain gets confused about distance, because the feeders/trees are close and the trailer is far. It can't decide which to focus on so, so it focuses on both. So you get two images.
Don't look at a nearby object first or remove the foreground, and voilà, no more double images.
Have you used mostly roofs before buying the SE? I tend to see this optical illusion much less through roofs, because the closer set barrels, particularly on mid-sized models, do not have much parallax effect.
If you look through a mid-sized roof and do the blink test - close your left eye and look through the right EP and then quickly open your left eye and close the right and look through the left EP, and go back and forth like that, you should notice a slight shift in the position of the image.
Do it the blink test with the SE, and you should notice a greater shift in image position when changing views from eye to eye.
Since porro objectives are spaced further apart than your eyes, the parallax effect is more noticeable in porros, particularly at closer distances.
This makes your eyes/brain more susceptible to optical illusions.
Here's another illusion, look at the "3-D" box on the site below.
If you move your eyes around the edges of the cube, it will shift perspective, the front "wall" will become the back wall and vice versa, because the drawing creates a perspective ambiguity.
http://www.illusion-optical.com/Optical-Illusions/Cube.php
Your eyes might eventually adjust to the 3-D/parallax effect of porro binoculars.
If not, you will have to take the bins away from your eyes after you focus close and rest them for a few seconds before looking far away and keep the foreground out of view (which is impossible in deep woods) or sell or trade your SE for a similar quality mid-sized roof such as the 8x32 LX.
Brock