Can you submit two different abstracts about the same data to two different conferences? We were working as a team to gather some data in the medical field and our research was concluded in the summer. I was the only member of the team that was interested in presenting the data so I contacted our senior who supervised the whole research about doing so. He sent me the data and I began writing my abstract for a conference next year. He then told me that he has already sent an abstract to a conference this year for the same data and it has been accepted for oral presentation. Our abstracts are obviously not the same and I am submitting to a different conference entirely but we are using the same data and trying to answer the same question. I am aware that it is forbidden to present data that has been published or presented before as I have submitted abstracts in the past and I have seen it in the rules section. However for the conference I want to send my abstract to, they don't mention anywhere that the results cannot have been published previously. I don't want to do something that is against the rules as I understand these conferences rely on publishing novel data. But its a conference on a totally different topic, a completely different abstract and they do not mention that the data cant have been published before. What should I do in this case?
In most experimental fields (to which I would definitely slot medicine), it's rather common to present results more than once at conferences.  The obvious reasons for doing this are that different conferences hit different audiences.  Also, that the researcher may be going to the conference to hear other talks, or even enjoy some travel (do not bind the mouths of the oxen!), not ONLY to publish his/her results.

Also I strongly advise to publish your results in a "real journal", widely circulated, not a conference proceedings, only.  [In most fields, CS/Math excluded.]  The conference(s) may have some boilerplate about "original research" or "peer reviewed conference proceedings" (the latter often a very poorly distributed set of volumes).  

You have to learn to play the game with that sort of thing (conference proceedings in experimental fields).  Your interests AND the interests of the field are much better served by eventually publishing in JAMA or some lesser but similar "real journal".  Give the conference enough so that it looks good, but not your whole case.  Maybe enough of the problem to flash the motivation (is of interest) and then a subsection of the results.  This is probably enough so that you can still publish the entire study in a real article (or set of them), in real, well-circulated and well-reviewed magazines.  Of course, cite the earlier conference proceedings (gives you as self cite also...woot!), so that you are not covering up doing the earlier publication.  But don't feel bashful about repeating the content from the earlier, page-limited conference proceedings, within your longer "real articles".