This happened to me at another school. My advisor told me to "accept" for the College but that the department knew I would not really come unless/until they came up with an attractive funding package and unless I did not accept an offer from another school. The advisor could not "hunt" for funding for me in the College until I "accepted" the offer of the College. So, I "accepted" the offer from the College but emailed my advisor and the department chair that my acceptance was provisional until a funding offer was made and until I received notification from other schools as I was doing a national search. The professors knew what was going on, and it is hoops jumping. Not all schools do this, so be careful not to offend people by appearing double-faced. I would suggest you see what your advisor recommends and be totally up front with her/him.