Why cutting from a surface gives different cross section in SolidWorks?

I'm trying to cut a section from turbine disk, to do that, since the section is irregular, I'm doing the following:
1. creating a surface between to blades, this surface twists towards the midle of the disk so that one of its sides matches the axle of the disk
2. making a circular pattern that creates the same numbers of surfaces as there are of blades, but only keeping to srufaces
3. using esch surface to make a surface cut (one from each side) and creat a section of the disk
The end result is something similar to this:
The problem is that, if I measure the surfaces created by the cuts, each will be different by 0,01mm². I tiny difference that keeps me from doing a cyclic symmetry in ANSYS.
SolidWorks doesn´t care for this difference, if I made a pattern of this solid, and merge it, all will be fine.
How to solve or get around this?
Thanks in advance