This article explains the trigger for the log message:
Error adding INET to PIM Register Encapsulation interface
The following messages will be logged frequently on the router if all interfaces are disabled on the [protocols pim] hierarchy and the tunnel services PIC are reset.
Jul 20 17:46:00.757 2013 ABC rpd[90452]: Error adding INET to PIM Register Encapsulation interface 172.18.252.34 to 172.18.252.33: File exists Jul 20 17:46:01.621 2013 ABC rpd[90452]: Error adding INET to PIM Register Encapsulation interface 172.18.252.34 to 172.18.252.33: File exists Jul 20 17:46:02.451 2013 ABC rpd[90452]: Error adding INET to PIM Register Encapsulation interface 172.18.252.34 to 172.18.252.33: File exists
The command set protocol pim interface all disable disables all interfaces that are not enabled explicitly in PIM including the 'pe-' and 'pd-' interfaces.
set protocol pim interface all disable
PIM removes the internal data structure for the 'pe-' and 'pd-' interfaces when the tunnel PIC is removed, and trying periodically to create the 'pe-' and 'pd-' once the tunnel PIC is brought online.
These messages are considered notifications and are not known to cause any impact.
Deactivate or remove the configuration set protocol pim interface all disable and configure only the interfaces which need to be included in PIM. The log messages will stop thereafter.