Some page moves are recorded in the database with a different comment ID in their recent changes entry and log entry despite the fact the comments have the same content. This seems to mostly happen with the Renameuser extension, but not exclusively.

Running the following query on the English Wikipedia database shows the first 100 of these page moves:

use enwiki_p;

SELECT rc_log_action, rc_this_oldid, rc_logid, rc_comment_id, log_comment_id, rev_comment_id, c1.comment_hash, c2.comment_hash, c3.comment_hash FROM recentchanges
JOIN logging ON log_id = rc_logid
JOIN revision ON rev_id = rc_this_oldid
JOIN comment c1 ON rc_comment_id = c1.comment_id
JOIN comment c2 ON log_comment_id = c2.comment_id
JOIN comment c3 ON rev_comment_id = c3.comment_id
WHERE rc_comment_id != log_comment_id
LIMIT 100;

From what I can tell, all the rc_comment_id cells in the added to recentchanges are using the same comment ID, but all the log_comment_id cells that are added to logging each use a different comment ID that is higher than the one used by the recent changes. For example: