From Wikipedia: Multiple submission is not plagiarism, but it is considered a serious academic misbehavior.
The following account is beyond multiple submission.
To Summarize:
  • [X] Submitted Sept 2013 to SIGMOD ... good solution (to be rejected in Nov)
  • [Y] submitted Oct 2013 to VLDB ... poor solution
  • Note 1: the first 3 authors of [X] and [Y] are the same, but in reverse order.
  • Note 2: [X] and [Y] are not double submission, the two solutions are not the same !!!
  • Note 3: [X] was very poorly presented. [Y] was very well presented.
  • Note 4: the second author is [W]
  • [Y] 1 Nov 2013: given up to 3 months to revise by VLDB
  • [X] resubmitted Nov 2013 to PODS (to be rejected)
  • [Y'] revision of [Y] 1st Jan 2014 ... poor -> good (similar to [X] ... complaints by [X])
  • first author of [X] complained to [Z], [Z] made sure that [X] was published in arXiv Jan 2014. [Y'] was stopped.
  • [Y''] revision of [Y'] 9th Jan 2014 ... good -> good (changed data format, still idea from [X])
  • [Y''] submitted 1 Feb 2014 as revision to VLDB
  • [Y''] accepted Mar 2014
  • [X] resumitted to VLDB, ICDE,... rejected
  • The first author of [X] has tried to improve the presentation of [X], which was also urged by [Z], but [W] refused.
  • [X] is a model example for "how to ensure rejection for a paper" or "how to hide your work by ingeniously obscure writing"

    The authority says that submissions like [X] and [Y] are fine, and that [Z] may get fired for voicing out, so now [Z] finds it necessary to voice out because one cannot back away from danger as such.
    [W] has published papers in SIGMOD 2010 and VLDB 2013 with [Z] for which [Z] has come up with the problem proposal, problem formulations, all the major ideas and algorithms and did almost all theoretical work, but since 2013, [W] has created dramatic scenes to claim all credits instead even in front of [Z] and others. People ought to believe in [W], because [Z] operates against the norm, which is hard to believe. What, then, shall we say ? That [Z] should operate otherwise ? By no means! For this is the way.
    At the end of 2013, [W] submitted a paper to SIGMOD, with main theorems proposed and proved by [Z], without notifying or including [Z]. [Z] informally informed the authority in a meeting with witness by the first author, but the authority now says that there is no recall of such a complaint. This has to be a very common routine happening so that it does not register at all. Possibly most submissions are like this.