Description of problem:
ssh-copy-id tries to detect that key is already present on the remote host.
It does by trying to log in there and checking for string 'Permission denied' in the error output. However one can have set custom loglevel which will not produce this output.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. ~/.ssh/config contains "LogLevel QUIET" for remote host
2. ssh-copy-id remote.host
WARNING: All keys were skipped because they already exist on the remote system.
asked for password and key is copied
openssh-clients-7.2p2-7.fc24 specifies log level inside ssh-copy-id
This is already fixed upstream  from commit in ssh-copy-id repo . It sounds reasonable to fix this also in RHEL7.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.