I think I know how the double http happened, when you open the image code that is already there and you have to get rid of it or paste over it. If you click so the existing http is still there but no longer highlighted you will end up with 2.

I always open the image I want to post to full size in photobucket then next to it is a list of links. If you click the direct link it automaticly copies it. Then paste that into the UBB box.

You can also paste that direct link right into where you type and just put [image] at the front and [/image] at the end manually.

I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!