1. A fiber optic sensing device comprising: an optical fiber including at least two fiber cores spaced apart so that mode coupling between the fiber cores is reduced; wherein each fiber core has an associated Rayleigh scatter signature and different segments of each fiber core correspond to a portion of the associated Rayleigh scatter signature; a frequency domain reflectometer coupled to the optical fiber configured to obtain a Rayleigh scatter pattern associated with each of multiple fiber segments from each core and use the Rayleigh scatter patterns to determine a strain parameter for each of the multiple fiber segments from each core; and a computing device configured to determine a position and/or shape of a portion of the fiber based on the determined strain parameters.