Fannie Mae & Freddie Mac's standard refinance programs limit the loan-to-value to 75%, however if your 1st mortgage is owned by Fannie or Freddie they have their Making Home Affordable refinance options up to 125% LTV/unlimited CLTV (you said you had 2 mortgages but I wasn't sure if that is 1 mortgage on your current home and this home or if it was 2 mortgages on this home).
Check the Fannie & Freddie loan lookup pages at http://www.makinghomeaffordable.gov/get-assistance/loan-look-up/Pages/default.aspx to see if either own your 1st mortgage.
Since you purchased it as a primary residence, a lot of lenders say they won't let you switch to an investment property, but most lenders will go from a primary residence to an investment property than vice versa, so I don't think you'll have as tough of a time as some may think. If your mortgage doesn't currently have mortgage insurance than even at a new LTV over 80% you won't have it on the new loan with these special programs, if your existing loan does have mortgage insurance then it may difficult to get a new policy on an investment property over 80% LTV (I am not aware of any PMI company insuring investment properties).
Your existing lender would probably have the easiest qualifying guidelines, but that doesn't mean they'll be easiest to get a loan through. Check with many places who offer the program to find out what options you have, as lenders are very "niche-y" with this program with varying layers of guidelines depending on how risk-tolerant each is (for example a lot will not even do investment properties on the program unless they are currently servicing the loan).
If your loan isn't owned by Fannie or Freddie, you won't have that as an option and would just have the regular 75% LTV refinance options from them, and then whatever non-conforming investment loan programs would be out there, which I doubt would finance much more than 75%.
We go up to 105% LTV with the program, all occupancies, whether we are currently servicing the existing loan or not. If you have any questions I'd be happy to answer them.... more