Merging new files from HEAD to branch

Hello everybody out there using CVS,

When I add a new file to a branch and then merge this file into the
HEAD, CVS keeps updating this file after changing between HEAD and
branch or vice versa by "cvs up -A" or "cvs up -r branch" although the
file itself hasn't been changed.
Files that were added before the creation of the branch aren't updated
after these commands, if they haven't changed. That's what I would
expect and also want cvs to do for the new file.

Kind regards,
Julia