When having a working copy on a samba share, i used to get alot of “Failed to add ‘XXX’: object of the same name already already exists”. It seems that the problem lies on the samba configuration.
SVN tries to move a readonly file.
The reason why the file is created read only, i do not know. But setting this in the share section in smb.conf solved the issue.
force create mode = 0664
i have been told that this in the global section also will do the trick
delete readonly = yes