Merge Request internal ids are colliding

I'm seeing a bug happening regularly where merge requests are created with the same issue numbers. I cannot find a way to reproduce at this time.

Example:

In Merge Request list: mr_list

In Merge Request detail: mr_detail

gitlabhq_production=# select id, iid, title from merge_requests WHERE iid=1010 LIMIT 10;
  id  | iid  |               title
------+------+------------------------------------
 1919 | 1010 | Item <redacted>
 1918 | 1010 | Sav 8955 <redacted>