pg_query & pg_last_oid

Hi All

In PHP

after sending a querry Im using pg_last_oid to get the oid.

Is a mix between two users that submit query simultaniusly accour ?

user A: insert into .......
user A: last oid 1
user B: insert into .......
user B: last oid 2

user A: pg_last_oid  = 2
user B: pg_last_oid  = 2

Can this happen ?
If so, what one can do to avoid it ?