you probably have a five wire unipolar stepper, see image. (Common = your E, Coil 1-4 = your A-D) Each coil is 8 ohms.
When you measure between A to B/C/D you measure two of the coils in series, i.e. A to B (Coil 1 to Coil 2). Resistors in series adds together, 8+8ohms=16ohms. So this is perfectly normal. (Coil1 to coil2/3/4 on the image below).
(Image borrowed from http://www.doc.ic.ac.uk/~ih/doc/stepper/others/)