It would be nice if there was some automatic method for this, but there isn't. You could have a mix of symbols with the same name, where some duplicate what's already in a file and some that are unique. To have something that automatically changes names when conflicts exist could result in unnecessary duplication, which could be another problem to deal with when you have to find the right ones to edit.
The best bet for now is to rename anything ahead of trying to copy them into another file.
it would have been very nice with a function to rename multiple symbols at the same time
but i asume there is no way to do this too?
thanks in advance
There isn't within Flash, but I can't say that a routine couldn't be created that might be able to do it.... it's beyond what I know. There have been times I've seen when people were told they could utilize some form of coding to create their own routines for manipulating things in the Flash editor, like automatically inserting keyframes every other one as an example I recall, but I recall nothing of what that involved... if it was really possible.
What you want would be a nice feature--maybe a third option to the two they currently offer (replace or not). Flash does have some built-in intelligence for making copies of symbols, which you've probably seen (appends Copy 1, etc) to a copy's name.