By the way, the customer has run into the issue *again* now since deleting
the duplicate rows about a week ago. There are three duplicates now. Again,
everything is identical between the versions except for the ctid. The
xmin/xmax are also identical:
=> select ctid, xmin, xmax, id from post where id in (1877554, 1885823,
1885824);
ctid | xmin | xmax | id
------------+---------+---------+---------
(28771,35) | 1651525 | 1651525 | 1877554
(28778,29) | 1651525 | 1651525 | 1877554
(28771,37) | 1651525 | 1651525 | 1885823
(28778,33) | 1651525 | 1651525 | 1885823
(28771,36) | 1651525 | 1651525 | 1885824
(28778,31) | 1651525 | 1651525 | 1885824
(6 rows)