tables ending with _copy appeared in the database

Dear community,

I've just noticed that in one of our databases many duplicate tables had
appeared all ending  in _copy. These tables are owned by postgres not
the db owner user, other than that they seem to be a replica from a
specific time in the past. I suspect that a failed backup might have
cased these, but I am not sure. I couldn't find any info tables ending
in _copy and also I thought that backups run in a transaction so even if
they create temporary tables, they should disappear even when the
backups fail.

Can you confirm that this was due to a failed backup? Is it safe to
delete all _copy tables? Should I do any additional housekeeping to
clean this up?
regards
Eliott