Upgrade creates duplicate foreign key constraints

create table a (id uuid primary key);
create table b (id uuid primary key);
alter table b add column if not exists aid uuid references a(id);
alter table b add column if not exists aid uuid references a(id);
\d b

                Table "public.b"
 Column | Type | Collation | Nullable | Default
--------+------+-----------+----------+---------
 id     | uuid |           | not null |
 aid    | uuid |           |          |
Indexes:
    "b_pkey" PRIMARY KEY, btree (id)
Foreign-key constraints:
    "b_aid_fkey" FOREIGN KEY (aid) REFERENCES a(id)
    "b_aid_fkey1" FOREIGN KEY (aid) REFERENCES a(id)

alter table b add column if not exists aid;
do $$
begin
  begin
    alter table b add constraint b_aid_fkey foreign key (aid) references a(id);
  exception
    when duplicate_object or duplicate_table then null;
  end;
end $$;

alter table b drop constraint if exists b_aid_fkey1;
alter table b drop constraint if exists b_aid_fkey2;
alter table b drop constraint if exists b_aid_fkey3;