Skins change on their own

I've noticed on some of the 50' Hi Cube box cars that the skins will change on their own after loading a saved session. I don't like graffiti on my trains and it is annoying when this happens especially if I am taking screenshots. I know graffiti is a fact of real life railroads these days, but the beauty of Trainz is that we can create the world we want. Can the graffitied skins just be removed totally from the car?

i got rid of a graffiti 100 ton coal hopper (CSX). it had necro on it. that wasn't the problem. the problem is i use at least 100 coal cars in a consist and the necro came up more than wanted more than once is not cool. i did get rid of the offending graffiti but it seems to have taken two skins. there was 4 now there is two.
graffiti doesn't bother me and there is some real pieces of art out there. as long as they don't paint over the car numbers i don't care

Some graffiti is very artistic, the people doing it are very talented. I just have issues with where they choose to practice their art, in general, but this isn't the place for that discussion.
To the question at hand, is removing unwanted skins from a multi skin item a case of deleting the unwanted skins, then renaming the remaining ones and changing the config, or is there something else that needs to be done?

it is better to clone then try to remove the offending car. for some reason i lost two skins but i just deal with it. it wasn't the graffiti that was the problem it was how often it showed up in the consist. what are the chances of a tagged car with the same tag showing up in a 100 car consist?