Hi Alex and Photoj,
thank you very much for your help in this matter. I had no idea that stopping down might reduce ghosting - this is a very helpful tip that I will certainly try!
Photoj, I think I can even see the effect of stopping down, given that the first one is F4 and the second one is F10. When I check the other shots I took form the same spot but with F16 and below, I see no ghosting. I'm sure the angle to the light has something to say as well, but probably not a parameter I can "manage" per se, I would guess.
I might have to overcome my stubbornness and allow my camera to use ISO800 and not limit it to ISO400 as I do now for night-shots.
If it keeps bugging me, I will have to give it a try to invest in better multi-coated UV filters as well. The ones I have are pretty "pedestrian" to say the least..lol.
Of course the issue of the much longer exposures and/or higher ISO comes in, but aren't those the eternal dynamics we deal with ?
Thank you very much for the insights and the tips, I really appreciate it