Hello, solved. This is not a postgres issue.
The system was used in HA-cluster with streaming replications. The hidden files I asked for were created probably by broken (killed) rsync. It uses such file-format for temporary files used during copying. This rsync is used by master to slave database synchronization (full on-line backup of master database to slave node) before starting postgres in hot-standby mode on slave the node... Best Regards, Andrej