I'm having a recurring issue on DB key violations, here's a log error output on that:

Jun  3 15:09:46 144227  ERROR: pua_dialoginfo [pua_dialoginfo.c:264]: __dialog_sendpublish(): bad reply or missing CONTACT hdr
Jun  3 15:10:01 723993  ERROR: presence [presentity.c:807]: update_presentity(): No E_Tag match a.1401768964.671509.1990.6
Jun  3 15:10:06 242334  WARNING: db_postgres [km_dbase.c:235]: db_postgres_submit_query(): postgres result check failed with code 7 (PGRES_FATAL_ERROR)
Jun  3 15:10:06 242370  WARNING: db_postgres [km_dbase.c:239]: db_postgres_submit_query(): postgres query command failed, connection status 0, error [ERROR:  duplicate key value violates unique constraint "pua_pua_idx"#012DETAIL:  Key (etag, tuple_id, call_id, from_tag)=(a.1401768964.671497.1902.6, , , ) already exists.#012]
Jun  3 15:10:06 243415  WARNING: db_postgres [km_dbase.c:235]: db_postgres_submit_query(): postgres result check failed with code 7 (PGRES_FATAL_ERROR)
Jun  3 15:10:06 243449  WARNING: db_postgres [km_dbase.c:239]: db_postgres_submit_query(): postgres query command failed, connection status 0, error [ERROR:  duplicate key value violates unique constraint "pua_pua_idx"#012DETAIL:  Key (etag, tuple_id, call_id, from_tag)=(a.1401768964.671497.1902.6, , , ) already exists.#012]
Jun  3 15:10:06 244458  WARNING: db_postgres [km_dbase.c:235]: db_postgres_submit_query(): postgres result check failed with code 7 (PGRES_FATAL_ERROR)
Jun  3 15:10:06 244487  WARNING: db_postgres [km_dbase.c:239]: db_postgres_submit_query(): postgres query command failed, connection status 0, error [ERROR:  duplicate key value violates unique constraint "pua_pua_idx"#012DETAIL:  Key (etag, tuple_id, call_id, from_tag)=(a.1401768964.671497.1902.6, , , ) already exists.#012]
Jun  3 15:10:06 244504  ERROR: db_postgres [km_dbase.c:247]: db_postgres_submit_query(): 0x7f21476b1910 PQsendQuery Error: ERROR:  duplicate key value violates unique constraint "pua_pua_idx"#012DETAIL:  Key (etag, tuple_id, call_id, from_tag)=(a.1401768964.671497.1902.6, , , ) already exists.#012 Query: update kamailio.pua set expires=1401807715,cseq=0,etag='a.1401768964.671497.1902.6',desired_expires=1401811600,version=2 where pres_uri='sip:208@freguesiadearroios.govoice.pt' AND pres_id='DIALOG_PUBLISH.440163220-35219-52@BJC.BGI.B.BAI' AND flag=1024 AND event=32
Jun  3 15:10:06 244521  ERROR: <core> [db_query.c:337]: db_do_update(): error while submitting query
Jun  3 15:10:06 244548  ERROR: db_postgres [km_dbase.c:537]: db_postgres_store_result(): invalid query, execution aborted
Jun  3 15:10:06 244560  ERROR: db_postgres [km_dbase.c:538]: db_postgres_store_result(): driver error: PGRES_FATAL_ERROR, ERROR:  duplicate key value violates unique constraint "pua_pua_idx"#012DETAIL:  Key (etag, tuple_id, call_id, from_tag)=(a.1401768964.671497.1902.6, , , ) already exists.#012
Jun  3 15:10:06 244584  WARNING: db_postgres [km_dbase.c:647]: db_postgres_update(): unexpected result returned
Jun  3 15:10:06 244591  ERROR: pua [pua.c:1076]: db_update(): while updating in database