What has caused this effect?

I took this photo this evening, when I got home and checked it on the camera I appear to have two suns.
I was using a K10d, with Pentax 28 - 80mm with a skylight filter.
Could this be refraction within the filter?
It doesn't trouble me, I'm just curious.

[IMG]http://i75.photobucket.com/albums/i296/Father_Ted/PHOTOS/IMGP9775_zpse5b65e6e.jpg[/IMG]

I am sure someone will be able to confirm either way but it looks like it may be the effect of the filter, I am sure I read somewhere that this can happen.

I had the same with uv/skylight filters, not just with the sun either, so took them off now, still carry the uv for the hazy days but I don't think it has been back out of its box.

Meant to add, I have ditched all filters now except ND Grads & Circular Polarizers and have noticed an increase in the IQ of my shots.

It is a ghost image caused by light reflecting from the lens back onto the rear surface of the filter, yet another good reason for not using them!

I have a few genuine Pentax Ghostless UV filters which are curved to prevent this effect happening. Although no longer made and they only come in 49 and 52mm fitting, you can pick them up on eBay. They were eyewateringly expensive when new.

OK...off with the filter unless needed.
I tend to keep it on to protect the lens, just in case.

Thanks guys.

I took a sunset shot in Rovies Greece,(see my portfolio) but have never experienced the problems that you mention.
I always keep the UV filter on my lenses,as it's so very much cheaper to replace a scratched filter than a lens!

I've done quite a few sunsets and not seen it before this. Must have been the angle of the camera to the sun maybe. Still as long as it was only the filter, I know what to watch out for.
I probably should have seen it in the viewfinder. I really should learn to slow down and look properly.