Release Notes mdi.fd_Ic:

The data in the DRMS series mdi.fd_V do not exactly match the data
that was contained in dsds.mdi__lev1_5__fd_Ic_01h. First of all, a
final platescale was calculated after the end of the MDI
mission. 

Secondly, the following known concerns exist:
The dsds series dsds.mdi__lev1_5__fd_Ic_01h has mixed 60-second and 30-second exposure images as well as mixed linearly and circularly polarized images. 

The images in mdi.fd_Ic are only the 60-second exposure images, all of which are linearly polarized. The other images will go into different series.